Tcl packaging guidelines

These conventions apply to Tcl packages in Fedora 9 and later. There are some aspects of Tcl in Fedora 7 and Fedora 8 that will conflict with these guidelines.

Naming Conventions

The name for all Tcl/Tk extensions must be prefixed with tcl-. This rule applies even for Tcl/Tk packages that are already prefixed with tcl in the name (see examples below). An optional Provides: foo is recommended to allow selecting the package based on the upstream name, as long as the upstream name is not excessively generic and does not conflict with an existing package name. Tk extensions have the option of adding additional Provides: with the prefix tk-.
Examples:

Name: tcl-bwidget
Provides: bwidget = %{version}-%{release}, tk-bwidget = %{version}-%{release}

Name: tcl-tclxml
Provides: tclxml = %{version}-%{release}

Name: tcl-thread

The exception to this naming rule are existing packages that provide both an extension and a shell, such as expect. However, note that providing a shell is strongly discouraged (see below).

Applications

Tcl and Tk applications must use a non-versioned interpreter name in shebang line. This is to prevent any unnecessary dependency on the version of the interpreter being used. Most dependencies are with specific Tcl extensions, not the command line applications. Nevertheless, if an application does require a specific version of Tcl, it should use the standard Tcl package system to express this, as well as an explicit Requires: tcl(abi) = 8.x in the spec file.

Bad:

#!/usr/bin/tclsh8.5

Good:

#!/usr/bin/tclsh
package require -exact Tcl 8.5

The same rules apply for Tk applications. The non-versioned wish interpreter name must be used.

Extensions

Since Fedora 9, %{_libdir} and %{_datadir} have been removed from the search path to optimize package loading times. Instead, Tcl extension packages must be installed in %{_datadir}/tcl8.x if they are noarch packages containing only Tcl code, or %{_libdir}/tcl8.x if they are arch-specific extensions containing shared libraries. Note that most Tcl extensions are not configured do install in these directories out of the box, and may need to use additional configure switches, patches, or script code in %install to move the files to the correct location.

Both arch-specific and noarch Tcl extensions must use

Requires: tcl(abi) = 8.6

to indicate which Tcl version (8.5 in F19 and F20, 8.6 in F21+) they were built against. This is necessary because the guidelines below require extensions to be installed into tcl-versioned directories, which are only used by a single version of Tcl. This does impose an inconvenience that all arch-specific and noarch extensions will need to be rebuilt for a new minor version of Tcl, but since new Tcl minor versions only appear once every few years, this should not be such a problematic inconvenience.

noarch packages

The following macros must be used at the top of the spec file to determine the correct installation paths:

%{!?tcl_version: %global tcl_version %(echo 'puts $tcl_version' | tclsh)}
%{!?tcl_sitelib: %global tcl_sitelib %{_datadir}/tcl%{tcl_version}}

In order for the macros to work, the package must also BuildRequires: tcl either directly, or indirectly with BuildRequires: tcl-devel

Merely adding the %{tcl_sitearch} and %{tcl_sitelib} is not enough to ensure that the packages get installed into the correct location. Most Tcl extensions will install into %{_libdir} by default. There are two ways to change this. For most noarch packages, you can use the --libdir and --datadir configure switches to change the installation directory:

%configure --libdir=%{tcl_sitelib} --datadir=%{tcl_sitelib}

For noarch packages that aren’t fixed by using --libdir, you can simply move the installation directory in the %install section of the spec file.

%install
rm -rf $RPM_BUILD_ROOT
make install DESTDIR=$RPM_BUILD_ROOT
install -d $RPM_BUILD_ROOT%{tcl_sitelib}
mv $RPM_BUILD_ROOT%{_datadir}/foobar%{version} $RPM_BUILD_ROOT%{tcl_sitelib}/foobar%{version}

It may also be acceptable to patch upstream’s configure script and Makefile to add additional flexibility for the install directory, but the packager is not required to do this.

arch-specific packages

The following macros must be used at the top of the spec file to determine the correct installation paths:

%{!?tcl_version: %global tcl_version %(echo 'puts $tcl_version' | tclsh)}
%{!?tcl_sitearch: %global tcl_sitearch %{_libdir}/tcl%{tcl_version}}

In order for the macros to work, the package must also BuildRequires: tcl either directly, or indirectly with BuildRequires: tcl-devel

While %{tcl_sitearch} is a symlink to %{tcl_sitelib} in Fedora 8 and earlier, in Fedora 9 it is an actual directory.

The --libdir flag for the configure script can often be used to set the correct installation directory:

%build
%configure --libdir=%{tcl_sitearch}

For most arch-specific packages, the --libdir flag for the configure script is also used to locate tclConfig.sh. Some of these arch-specific packages will break if --libdir is redirected to %{tcl_sitearch}. For packages that can’t handle alternate values for --libdir, you can simply move the installation directory in the %install section of the spec file:

%install
make install DESTDIR=$RPM_BUILD_ROOT
install -d $RPM_BUILD_ROOT%{tcl_sitearch}
mv $RPM_BUILD_ROOT%{_libdir}/foobar%{version} $RPM_BUILD_ROOT%{tcl_sitearch}/foobar%{version}

Arch-specific packages can be generally grouped into three categories: those that provide a shell, those that provide a fooConfig.sh file and a shared library for linking, and those that only provide a shared library for dlopen().

No shells: Very few Tcl extension packages provide a shell. Providing a shell for an extension is frowned upon. The extension’s shared library can be dynamically loaded into a Tcl interpreter through the standard package require ... mechanism without providing a shell that automatically loads the shared library. The exceptions to this rule are the shells that are commonly expected to be present on a system, including Tk (wish) and Expect (expect, expectk).

-devel subpackage for fooConfig.sh: Some arch-specific Tcl extensions provide a shared library and a corresponding fooConfig.sh file with instructions for linking against the library. The shared library for such packages must be installed into %{_libdir} so that it can be found at runtime by applications that link against it. Unfortunately, the pkgIndex.tcl file in the package directory often references the shared library with a relative path. There are two ways to fix this. First, the maintainer can choose to keep the installation directory as %{_libdir}, and make a symlink to %{tcl_sitearch}. Second, the maintainer can choose to patch the pkgIndex.tcl file to contain an appropriate path to the shared library. Either solution is acceptible.

fooConfig.sh files must be placed in a -devel subpackage. This may require some sed magic to modify fooConfig.sh so that the paths to the libraries and headers are still correct.

No dlopen()'d libraries in %{_libdir}: If the extension does not provide a fooConfig.sh file, then the shared library must not be installed directly in %{_libdir}, but in the package-specific installation directory in %{tcl_sitearch} instead. This may require a patch to update the extension’s pkgIndex.tcl file to look for the shared library in the correct location.

Stubs are ok if put in -devel subpackage: Some Tcl extensions provide a static 'stub' library. Stub libraries are a Tcl-ism to provide version-independent dynamic linking on a variety of platforms. These are not normal static libraries that provide the library’s actual functionality, but instead provide a level of indirection pointing to the shared library. These stub libraries do not have the same static linking issues that are generally frowned upon in Fedora, and thus are acceptable. If a package provides such a stub library, it must be placed in a -devel subpackage. More information on stubs can be found on the Tcl wiki: https://wiki.tcl-lang.org/page/Stubs

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