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\begin_body

\begin_layout Title
Automake
\end_layout

\begin_layout Author
Let Automake do the work :)
\end_layout

\begin_layout Standard
\begin_inset CommandInset toc
LatexCommand tableofcontents

\end_inset


\end_layout

\begin_layout Section
Introduction
\end_layout

\begin_layout Standard
As we have discussed about the Automake in the Autotools,
 it is seems very tempting to start generate Makefiles for your projects and generate a Makefile for each module with a master Makefile at the top of project directory structure.
 However,
 there is a very good and informative paper by Peter Miller regarding 
\begin_inset Quotes eld
\end_inset


\begin_inset CommandInset href
LatexCommand href
name "Recursive Makefiles are Considered Harmful"
target "https://wikileaks.org/ciav7p1/cms/files/auug97.pdf"
literal "false"

\end_inset


\begin_inset Quotes erd
\end_inset

.
 As per this paper,
 projects with Recursive Makefiles build system are not very optimal for building projects,
 especially which are very large in size.
 But,
 writing a single Makefile for a very large project or even generating it using Automake is not very manageable,
 which is good argument.
 So,
 a 
\begin_inset CommandInset href
LatexCommand href
name "blog"
target "http://karelzak.blogspot.com/2013/02/non-recursive-automake.html"
literal "false"

\end_inset

 by Karel Zak suggest that we can create a single resulting Makefile from bunch of 
\shape italic
include files
\shape default
 which are included in main Makefile.am.
 Therefore,
 our first goal is to create a build system which is optimal.
\end_layout

\begin_layout Standard
\begin_inset Float figure
placement document
alignment center
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename images/project-tree.png

\end_inset


\end_layout

\begin_layout Plain Layout
\align center
\begin_inset Caption Standard

\begin_layout Plain Layout
Project structure
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Section
Enabling Automake in configure.ac
\end_layout

\begin_layout Standard

\size normal
Just for the introduction,
 lets briefly understand what's configure.ac is?
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

configure.ac is the input file which is used by Autoconf to generate configure which is used to setup the environment for project compilation.
 In other word,
 this script allows us to configure our project build system.
 Detailed discussion over this is done in 
\begin_inset CommandInset href
LatexCommand href
name "Autoconf"
target "Autoconf.html"
type "file:"
literal "false"

\end_inset

 tutorial.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Much of the configure.ac script can be generated automatically based on the existing project tree or even updated based on the the current status.
 This automatic generation of configure.ac script is done using autoscan script.
 Note,
 that as the project structure grows,
 we don't have to create new configure.ac every time.
 Instead,
 autoscan will read the existing configure.ac and improve upon it.
 The resulting output of the autoscan is configure.scan and autoscan.log.
 configure.scan can be change to configure.ac to use by autoconf for configuration of the project.
\begin_inset Newline newline
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\begin_inset Newline newline
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The output of autoscan looks like:
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\end_inset


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\end_inset


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offset "0.5ex"
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height "1pt"

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\end_layout

\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true,tabsize=10"
inline false
status open

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
# Process this file with autoconf to produce a configure script.
    -*- Autoconf -*- 
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
AC_PREREQ([2.71]) 
\end_layout

\begin_layout Plain Layout
AC_INIT([FULL-PACKAGE-NAME],
 [VERSION],
 [BUG-REPORT-ADDRESS]) 
\end_layout

\begin_layout Plain Layout
AC_CONFIG_SRCDIR([foo/myprog.c]) 
\end_layout

\begin_layout Plain Layout
AC_CONFIG_HEADERS([config.h]) 
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
# Checks for programs.
\end_layout

\begin_layout Plain Layout
# This below is added only for C++ files.
\end_layout

\begin_layout Plain Layout
AC_PROG_CXX AC_PROG_CC 
\end_layout

\begin_layout Plain Layout
\align center

\end_layout

\begin_layout Plain Layout
# Checks for libraries.
 
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
# Checks for header files.
\end_layout

\begin_layout Plain Layout
# Checks for typedefs,
 structures,
 and compiler characteristics.
 
\end_layout

\begin_layout Plain Layout
AC_CHECK_HEADER_STDBOOL 
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
# Checks for library functions.
 
\end_layout

\begin_layout Plain Layout
AC_CONFIG_FILES([Makefile]) 
\end_layout

\begin_layout Plain Layout
AC_OUTPUT
\begin_inset Caption Standard

\begin_layout Plain Layout

\shape italic
configure.ac generated from autoscan.
\end_layout

\end_inset


\end_layout

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offset "0.5ex"
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height "1pt"

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\begin_layout Standard

\size normal
Note that the generated script is not enabled to use Automake tool the generate the Makefiles from Makefile.am input files.
 Oh wait!
 Didn't we just say that Automake generates Makefiles automatically for the project.
 Well,
 lets address that in the next section.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset

Now,
 to enable the Automake in this build system,
 we need to add one single line onto the above script.
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\end_inset


\begin_inset Newline newline
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\begin_layout Standard
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lstparams "language=bash,basicstyle={\footnotesize\ttfamily}"
inline false
status open

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
AC_PREREQ([2.71])
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
AC_INIT([FULL-PACKAGE-NAME],
 [VERSION],
 [BUG-REPORT-ADDRESS])
\end_layout

\begin_layout Plain Layout
AC_INIT_AUTOMAKE
\end_layout

\begin_layout Plain Layout
AC_CONFIG_SRCDIR([creational-pattern/src/MazeGame.cpp])
\end_layout

\begin_layout Plain Layout
AC_CONFIG_HEADERS([config.h])
\begin_inset Caption Standard

\begin_layout Plain Layout

\shape italic
Automake enabled
\end_layout

\end_inset


\end_layout

\end_inset


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offset "0.5ex"
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Executing the autoreconf -i command will now make the build system of project,
 Automake enabled.
\end_layout

\begin_layout Section
What is a Makefile.am file?
\end_layout

\begin_layout Standard

\size normal
It is just like a regular Makefile,
 but with comparatively less Makefile code and some syntactically specific to Automake.
 But,
 why Automake needs some input file at the first place to generate a output Makefile.
 Well,
 the main intent of the Automake tool is to generate a Makefile which mostly comprises of boilerplate code.
 Since GCS enforce lot of standard rules,
 this leads to lot of code begin boilerplate which makes it very redundant to write it by hand and also making sure that it is logically correct.
 Here,
 Automake comes in handy as it generates a 
\begin_inset Quotes eld
\end_inset

complete
\begin_inset Quotes erd
\end_inset

 Makefile which is compliant to GCS.
 Another benefit of using Automake is,
 it has automatic dependency tracking capability which allows the tracking of header files changes which are included in the source files.
 It is annoying problem where change in header files are often not reflected in the compiled build due to missing dependency checks and Automake handles it very gracefully to ensure the dependency checks are efficiently managed.
\end_layout

\begin_layout Section
Preparing the structure
\end_layout

\begin_layout Standard
Since our goal is to create a non-recursive build system of Makefiles using Automake,
 all the targets rules should appear in the top-makefile which may tell you that we may need to write a big Makefile.am for a project which is at the top of project directory.
 Fortunately,
 Automake can still create a single Makefile from bunch of input *.am files.
 This makes it super manageable.
 Writing bunch of 
\begin_inset Quotes eld
\end_inset

Makemodule.am
\begin_inset Quotes erd
\end_inset

 for each sub-directories of the project and including them in top Makefile.am will help us in completing our goal.
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
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\begin_inset CommandInset line
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offset "0.5ex"
width "100col%"
height "1pt"

\end_inset


\end_layout

\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
bin_PROGRAMS =
\end_layout

\begin_layout Plain Layout
man_MANS =
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
include foo/Makemodule.am
\end_layout

\begin_layout Plain Layout
include bar/Makemodule.am
\end_layout

\begin_layout Plain Layout
\begin_inset Caption Standard

\begin_layout Plain Layout

\shape italic
Makefile.am in root directory.
\end_layout

\end_inset


\end_layout

\end_inset


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offset "0.5ex"
width "100col%"
height "1pt"

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\begin_inset Newline newline
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Here,
 we can see that defining the variable at the top of top Makefile.am and then using it in the Makemodule.am in the sub-directories.
\begin_inset Newline newline
\end_inset

For ex,
 in 
\series bold
foo/Makemodule.am
\series default
:
\begin_inset Newline newline
\end_inset


\begin_inset Newline newline
\end_inset


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offset "0.5ex"
width "100col%"
height "1pt"

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\end_layout

\begin_layout Standard
\begin_inset listings
lstparams "language=bash,basicstyle={\footnotesize\ttfamily},breaklines=true"
inline false
status open

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
bin_PROGRAMS += myprog					# PLV
\end_layout

\begin_layout Plain Layout
man_MANS += foo/myprog.8
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
myprog_SOURCES = foo/myprog.c 
\backslash
			# PSV
\end_layout

\begin_layout Plain Layout
                 foo/myprog-utils.c
\end_layout

\begin_layout Plain Layout
\begin_inset Caption Standard

\begin_layout Plain Layout

\shape italic
Makemodule.am in foo directory of project.
\end_layout

\end_inset


\end_layout

\end_inset


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offset "0.5ex"
width "100col%"
height "1pt"

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\begin_inset Newline newline
\end_inset

Here in Makefile.am and Makemodule.am,
 we are using two important types of variables.
 These are 
\series bold
Product List Variable
\series default
 and 
\series bold
Product Source Variable
\series default
.
\end_layout

\begin_layout Subsection
Product List Variable:
\end_layout

\begin_layout Standard
Products of the build systems are specified to the Makefile.am using 
\shape italic
Product List variable (PLV)
\shape default
.
 These are class of variables which have special meaning to Automake.
 They tell what are the resultant output of the Makefiles or build system that will be generated after the successful completion of the build process.
 This variable consist of white-space-separated list of products and the variable (as you can see in above example) consist of two major parts separated by a underscore.
\begin_inset Newline newline
\end_inset

These two components are:
\end_layout

\begin_layout Itemize
bin:
 Prefix
\end_layout

\begin_layout Itemize
PROGRAMS:
 Primary
\end_layout

\begin_layout Standard
The 
\shape italic
bin 
\shape default
portion of the PLV represent a 
\shape italic
installation location prefix
\shape default
.
 This is used to define the installation location for the list of products which are mentioned in the PLV.
 The GCS defines many installation locations.
 However,
 make variable ending with 
\shape italic
dir 
\shape default
,
 whose value is a file-system location,
 is a viable installation location and can be used as prefix in a Automake PLV.
\begin_inset Newline newline
\end_inset

What we mean here is that any 
\series bold
make
\series default
 variable ending with 
\family typewriter
dir,
 
\family default
for example 
\family typewriter
$(bindir)
\family default
,
 with a installation location value can be used by Automake to produce 
\family typewriter
install 
\family default
rule which will install the list of products to the 
\family typewriter
$(bindir)
\family default
 location.
 However,
 only those products will be installed that are mentioned in the PLV which have prefix 
\family typewriter
bin
\family default
 as mentioned in the above example (bin_PROGRAMS) and PROGRAMS is termed as Primary which represent the type of product that is expected to be produced,
 which in this case is the list of binary files.
\begin_inset Newline newline
\end_inset

Automake by default recognizes 4 type of variable which they can be treated as installation locations and they have a prefix pkg.
 These variables are:
\end_layout

\begin_layout Itemize

\family typewriter
pkgincludedir
\end_layout

\begin_layout Itemize

\family typewriter
pkgdatadir
\end_layout

\begin_layout Itemize

\family typewriter
pkglibexecdir
\end_layout

\begin_layout Itemize

\family typewriter
pkglibdir
\end_layout

\begin_layout Standard
These pkg version of standard 
\family typewriter
libdir
\family default
,
 
\family typewriter
includedir
\family default
,
 
\family typewriter
datadir
\family default
 and 
\family typewriter
libexecdir 
\family default
indicates that the installation of the products listed in the PLV equivalent variable should be installed in the sub-directory of these location mentioned in these standard make variable where the sub-directory is named after the package.
 For example,
 our Project which is named as 
\shape slanted
Project
\shape default
 in our Figure 1,
 will have binary files (like 
\shape slanted
myprog
\shape default
) installed in the 
\shape slanted
Project
\shape default
 sub-directory of the 
\series bold
bin
\series default
 system directory.
 And yes,
 we can change the installation directory from 
\series bold
bin
\series default
 to any other directory by overriding the value of the 
\family typewriter
$(bindir)
\family default
 variable in Makefile.
\begin_inset Newline newline
\end_inset

We can also provide our own PLV custom prefix which represent a variable,
 having the location for installation of some list of products.
 For example,
 for installation of some XML files to a custom location,
 we can define a xmldir variable having value for the installation path and a PLV xml_DATA having value a list of xml files which will be installed in the installation path.
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\begin_layout Standard
\begin_inset listings
inline false
status open

\begin_layout Plain Layout
xmldir = $(datadir)/xml
\end_layout

\begin_layout Plain Layout
xml_DATA = file1.xml file2.xml file3.xml ...
\end_layout

\begin_layout Plain Layout
\begin_inset Caption Standard

\begin_layout Plain Layout
Custom PLV with variable in Makefile.am
\end_layout

\end_inset


\end_layout

\end_inset


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offset "0.5ex"
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Installation location can default values which are either defined by Automake or by user itself.
 However,
 these default value can be overridden using the argument passed while running the configure script or make command.
 If we don't want to install certain products to the installation location,
 Automake generated rules ensures to generate rules to handle such situations.
 For example,
 if we don't want to install binary and library files and only want to install the data files,
 we can pass the command 
\family typewriter
make bindir='' libdir='' install
\family default
.
 
\end_layout

\begin_layout Subsection
Prefix Not Associated with Installation
\end_layout

\begin_layout Standard
Sometimes,
 we don't want certain products to installed anywhere.
 That's why we have certain prefix which are not associated with any installation location.
 There are 3 main such prefix:
\end_layout

\begin_layout Itemize

\family typewriter
noinst
\family default
:
 This signifies that the product listed in a variable with this prefix is not to be installed anywhere in the system after the build process.
 It could be a 
\shape italic
convenience
\shape default
 static library which is only used to build a final product.
\end_layout

\begin_layout Itemize

\family typewriter
check
\family default
:
 The products listed will be build only when 
\family typewriter
make check
\family default
 command is used.
 These products are only build for testing purpose.
\end_layout

\begin_layout Itemize

\family typewriter
EXTRA
\family default
:
 This signifies the list of products which may be conditionally build and eventually,
 installed.
 This types of configuration control is possible via 
\family typewriter
\shape slanted
configure
\family default
\shape default
 script where we pass some argument to it and prompts to build some 
\begin_inset Quotes eld
\end_inset

extra
\begin_inset Quotes erd
\end_inset

 products.
 However,
 enabling such feature of autoconf and automake is not as simple as above two.
 Go through the below illustration:
\end_layout

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offset "0.5ex"
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\end_inset


\end_layout

\begin_layout Standard
\begin_inset listings
lstparams "basicstyle={\rmfamily}"
inline false
status open

\begin_layout Plain Layout
AC_INIT(...)
\end_layout

\begin_layout Plain Layout
...
\end_layout

\begin_layout Plain Layout
optional_programs=
\end_layout

\begin_layout Plain Layout
AC_SUBST([optional_programs])
\end_layout

\begin_layout Plain Layout
...
\end_layout

\begin_layout Plain Layout
if test "x$(build_opt_prog)" = xyes;
 then
\end_layout

\begin_layout Plain Layout
  optional_programs=$(optional_programs) optprog		### 1 ###
\end_layout

\begin_layout Plain Layout
fi
\end_layout

\begin_layout Plain Layout
...
\end_layout

\begin_layout Plain Layout

\end_layout

\begin_layout Plain Layout
\begin_inset Caption Standard

\begin_layout Plain Layout
A shell script code in configure.ac for building 
\series bold
optprog
\series default
 product conditionally.
\end_layout

\end_inset


\end_layout

\end_inset


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\begin_layout Plain Layout
EXTRA_PROGRAMS = optprog						### 2 ###
\end_layout

\begin_layout Plain Layout
bin_PROGRAMS = myprog $(optional_programs)	  ### 3 ###
\begin_inset Caption Standard

\begin_layout Plain Layout
Using the EXTRA prefix to conditionally build products in Makefile.am
\end_layout

\end_inset


\end_layout

\end_inset


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In Listing 6 ### 1 ###,
 
\series bold
optprog
\series default
 is appended to an Autoconf substitution variable called 
\family sans
optional_program
\family default
.
 The 
\family sans
EXTRA_PROGRAMS 
\family default
variable at ### 2 ### in Listing 7 list 
\family sans
optprog,
 
\family default
as a product that may or may not be build.
 This redundant information of 
\family sans
EXTRA_PROGRAMS 
\family default
in Makefile.am make it ensure that Automake knows that optprog is a optional product and make the resultant Makefile with appropriate script.
 This make sure that even if 
\series bold
optprog
\series default
 is not mentioned in 
\family typewriter
$(optional_programs)
\family default
 variable in some build.
\end_layout

\begin_layout Subsection
Primaries
\end_layout

\begin_layout Standard

\shape italic
Primaries
\shape default
 represent type of product which is generated by this build system.
 That's it!
 What are these type of files?
 
\begin_inset Newline newline
\end_inset

These files can be executable,
 libraries,
 config files in terms of xml,
 json and event normal txt files.
 Wait,
 normal txt files?
 Well,
 what it means is that some products (not exactly) of build system are not actually generated by the build system.
 These are part of the project and we will need these files while executing the software in our system after the build process of that software.
 For example,
 C or C++ language have the prototype of the function or API written in header files (.h or .hpp) which allows the user of the library to make there software aware of these API before using it and enables in linking the implementation to the function calls while in the linking process of the build system.
 So,
 the main intent of this long boring example is to provide a context on why we have different kind of primaries as this helps in differentiating the type of product to Automake and hence generate rules in resultant Makefile accordingly.
 Interestingly,
 we can define our own primaries,but beware,
 we need to write the rules for those on our own in Makefile.am.
\end_layout

\begin_layout Standard
Let us see the default primaries supported by Automake.
\end_layout

\begin_layout Itemize

\series bold
PROGRAMS
\series default
:
 These are binary executable programs.
\end_layout

\begin_layout Itemize

\series bold
LIBRARIES/LTLIBRARIES
\series default
:
 The LIBRARIES primary enables Automake to generate rules for building static libraries using system compiler and librarian (
\series bold
ar
\series default
).
 The LTLIBRARIES also do the same thing but to build 
\shape italic
libtool
\shape default
 shared libraries which are generated by executing 
\shape italic
libtool scripts
\shape default
.
 The installation of these products are limited to 
\family typewriter
$(libdir)
\family default
 or 
\family typewriter
$(pkglibdir)
\family default
.
 
\end_layout

\begin_layout Itemize

\series bold
SCRIPTS
\series default
:
 Scripts are generally handwritten which may be a part of project,
 however,
 Automake don't have the assumption that it will not make any rules to build the scripts or they are static files in the project.
 The scripts can be generated from handwritten rules in Makefile.am files,
 sometimes by processing a input file using the sed or awk utility tools.
 Even if the static script are present in the project and is intended to be distributed with the project tarball,
 then 
\series bold
dist
\series default
 modifier should be used with 
\series bold
SCRIPT
\series default
 primary.
 The installation location for scripts includes 
\family typewriter
$(bindir)
\family default
,
 
\family typewriter
$(sbindir)
\family default
,
 
\family typewriter
$(libexecdir)
\family default
,
 and 
\family typewriter
$(pkgdatadir)
\family default
.
\end_layout

\begin_layout Itemize

\series bold
DATA
\series default
:
 Data files are similar to what scripts files are intended for and can be distributed with project tarball and for that we can use 
\series bold
dist
\series default
 modifier with 
\series bold
DATA
\series default
 primary.
 The installation location for these type of files are 
\family typewriter
$(datadir)
\family default
,
 
\family typewriter
$(sysconfdir)
\family default
,
 
\family typewriter
$(sharedstatedir)
\family default
 and 
\family typewriter
$(localstatedir)
\family default
.
 
\end_layout

\begin_layout Itemize

\series bold
HEADERS
\series default
:
 Headers files are just like static files but are used for building of the project.
 These files generally contained the public interface of the installed libraries which can be used by other projects for using the libraries functionality.
 The PLV for these type of files are pkginclude_HEADERS and include_HEADERS and the installation locations are
\family typewriter
 $(includedir)
\family default
 and 
\family typewriter
$(pkgincludedir)
\family default
.
\end_layout

\begin_layout Standard
There are also other types of primaries that Automake supports,
 but we will currently discuss about the ones which are used the most.
 The rest of the commonly used primaries are 
\series bold
MANS
\series default
,
 
\series bold
TEXTINFOS
\series default
,
 
\series bold
PYTHON
\series default
,
 
\series bold
JAVA
\series default
,
 etc.
\end_layout

\begin_layout Subsection
Product Source Variable
\end_layout

\begin_layout Standard
If you notice,
 the second line in Listing 7 is an example of Automake 
\shape italic
product source variable
\shape default
 (PSV).
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"

\end_inset


\end_layout

\begin_layout Standard
\begin_inset listings
inline false
status open

\begin_layout Plain Layout
[modifier-list]product_SOURCES = file1 file2 ...
 fileN
\end_layout

\end_inset


\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"

\end_inset

Just like PLV which represent list of products,
 PSV represent list of files on which the product is dependent on.
 These are the source files which are used to build the products of the projects.
 Only characters that are allowed in make variables (letters,
 numbers,
 and the at sign) are allowed in the product tag of a PSV.
 So,
 Automake converst illegal characters into underscores.
\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"

\end_inset


\end_layout

\begin_layout Standard
\begin_inset listings
inline false
status open

\begin_layout Plain Layout
lib_LIBRARIES = libc++.a
\end_layout

\begin_layout Plain Layout
libc___a_SOURCES = ...
\begin_inset Caption Standard

\begin_layout Plain Layout
Illegal make variable characters are converted to underscores in product tags.
\end_layout

\end_inset


\end_layout

\end_inset


\begin_inset CommandInset line
LatexCommand rule
offset "0.5ex"
width "100col%"
height "1pt"

\end_inset


\end_layout

\begin_layout Subsection
PLV and PSV Modifiers
\end_layout

\end_body
\end_document