diff options
Diffstat (limited to 'doc/intro2.cli')
| -rw-r--r-- | doc/intro2.cli | 113 |
1 files changed, 94 insertions, 19 deletions
diff --git a/doc/intro2.cli b/doc/intro2.cli index 1d62ee6..69cfbee 100644 --- a/doc/intro2.cli +++ b/doc/intro2.cli @@ -39,7 +39,7 @@ $ b $ ./hello $ edit repositories.manifest # add https://example.org/libhello.git -$ edit manifest # add 'depends: libhello ^ 1.0.0' +$ edit manifest # add 'depends: libhello ^1.0.0' $ edit buildfile # import libhello $ edit hello.cxx # use libhello $ b @@ -108,8 +108,9 @@ hello/ ├── .bdep/ ├── build/ ├── hello/ +│ ├── hello.cxx │ ├── buildfile -│ └── hello.cxx +│ └── testscript ├── buildfile ├── manifest └── repositories.manifest @@ -135,9 +136,17 @@ $ cat hello/hello.cxx #include <iostream> -int main () +using namespace std; + +int main (int argc, char* argv[]) { - std::cout << \"Hello, World!\" << std::endl; + if (argc < 2) + { + cerr << \"error: missing name\" << endl; + return 1; + } + + cout << \"Hello, \" << argv[1] << '!' << endl; } \ @@ -153,7 +162,7 @@ $ cat hello/buildfile libs = #import libs += libhello%lib{hello} -exe{hello}: {hxx ixx txx cxx}{*} $libs +exe{hello}: {hxx ixx txx cxx}{*} $libs test{testscript} \ As the name suggests, this file describes how to build things. While its @@ -161,12 +170,33 @@ content might look a bit cryptic, let's try infer a couple of points without going into too much detail (the details are discussed in the following sections). That \c{exe{hello\}} on the left of \c{:} is a \i{target} (executable named \c{hello}) and what we have on the right are -\i{prerequisites} (C++ sources files). This \c{buildfile} uses +\i{prerequisites} (C++ sources files, libraries, etc). This \c{buildfile} uses \l{b#name-patterns wildcard patterns} (that \c{*}) to automatically locate all -the source files. This means we don't have to edit our \c{buildfile} every +the C++ source files. This means we don't have to edit our \c{buildfile} every time we add a source file to our project. There also appears to be some infrastructure for importing (commented out) and linking libraries (that -\c{libs} variable). We will see how to use it in a moment. +\c{libs} variable). We will see how to use it in a moment. Finally, +\c{buildfile} also lists \c{testscript} as a prerequisite of \c{hello}. This +file tests our program. Let's take a look inside: + +\ +: basics +: +$* 'World' >'Hello, World!' + +: missing-name +: +$* 2>>EOE != 0 +error: missing name +EOE +\ + +Again, we are not going into detail here (see \l{testscript#intro Testscript +Introduction} for a proper introduction), but to give you an idea, here we +have two tests: the first (with id \c{basics}) verifies that our program +prints the expected greeting while the second makes sure it handles the +missing name error condition. Tests written in Testscript are concise, +portable, and executed in parallel. Next up is \c{manifest}: @@ -179,7 +209,7 @@ summary: hello executable project license: proprietary url: https://example.org/hello email: you@example.org -#depends: libhello >= 1.0.0 +#depends: libhello ^1.0.0 \ The \c{manifest} file is what makes a build system project a \i{package}. It @@ -301,6 +331,9 @@ hello configured 0.1.0-a.0.19700101000000 $ b <...> +$ b test +<...> + $ hello/hello Hello, World! \ @@ -314,6 +347,9 @@ hello configured 0.1.0-a.0.19700101000000 $ b ../hello-clang/hello/ ... +$ b test: ../hello-clang/hello/ +... + $ ../hello-clang/hello/hello/hello Hello, World! \ @@ -399,11 +435,11 @@ build system and package manager (for example, when a build bot is building a package for CI). Note also that strictly speaking \c{build2} is not C/C++-specific; its build -system is general enough to handle any DAG-based operations and its -package/project dependency managers can be used for any compiled language.| +model is general enough to handle any DAG-based operations and its +package/project dependency management can be used for any compiled language.| -\N|As we will see in moment, \c{build2} also integrates with your VCS in order -to automate project versioning. Note that currently only \c{git(1)} is +\N|As we will see in a moment, \c{build2} also integrates with your VCS in +order to automate project versioning. Note that currently only \c{git(1)} is supported.| Let's now move on to the reason why there is \i{dep} in the \c{bdep} name: @@ -510,14 +546,53 @@ $ bdep new -t lib -l c++ libhello | Next we edit the \c{manifest} file (again, found in the root of our project) -and specify the version constraint for \c{libhello}: +and specify the dependency on \c{libhello} with optional version constraint. +For example: \ -depends: libhello >= 1.0.0 (@@ ^) +depends: libhello ^1.0.0 \ -Next we edit \c{hello/buildfile} and import the \c{libhello} library into our -build: +Let's discuss briefly version constraints (for details see the +\l{bpkg#manifest-package-depends \c{depends}} value documentation). A version +constraint can be expressed with a comparison operator (\c{==}, \c{>}, +\c{<}, \c{>=}, \c{<=}), a range shortcut operator (\c{~} and \c{^}), or a +range. Here are a few examples: + +\ +depends: libhello == 1.2.3 +depends: libhello >= 1.2.3 + +depends: libhello ~1.2.3 +depends: libhello ^1.2.3 + +depends: libhello [1.2.3 1.2.9) +\ + +You may already be familiar with the tilda (\c{~}) and caret (\c{^}) +constraints from dependency managers for other languages. To recap, tilda +allows upgrades to any further patch versions while caret also allows upgrade +to further minor versions. They are equivalent to the following ranges: + +\ +~X.Y.Z [X.Y.Z X.Y+1.0) + +^X.Y.Z [X.Y.Z X+1.0.0) if X > 0 +^0.Y.Z [0.Y.Z 0.Y+1.0) if X == 0 +\ + +\N|Zero major version component is customarily used during early development +where the minor version effectively becomes major. As a result, the tilde +constraint has a special treatment of this case.| + +Unless you have good reasons not to (for example, a dependency does not use +semantic versioning) we suggest that you use the \c{^} constraint which +provides a good balance between compatibility and upgrdability with \c{~} +being a more conservative option. + +Ok, we've specified where our package comes from (\c{repositories.manifest}) +and which versions we find acceptable (\c{manifest}). The next step is to edit +\c{hello/buildfile} and import the \c{libhello} library into our build: \ import libs += libhello%lib{hello} @@ -534,7 +609,7 @@ int main () } \ -\N|You are probably wondering why we have to specify this often repeating +\N|You are probably wondering why we have to specify this somewhat repeating information in so many places. Let's start with the source code: we can't specify the version constraint and location there because it will have to be repeated in every source file that uses the dependency. @@ -563,7 +638,7 @@ to your project: \ repositories.manifest # add https://example.org/libhello.git -manifest # add 'depends: libhello ^ 1.0.0' (@@ ^) +manifest # add 'depends: libhello ^1.0.0' buildfile # import libhello hello.cxx # use libhello \ |