Automatic dependencies

[Paul Wolneykien]

22.09.2010 09:01, Peter Lobsinger пишет:
>>   Information about static dependencies is a very important if you want to
>> >  get a stable software distribution. If one program can not be run without
>> >  another program you should install both of them. In the form of a high-level
>> >  language source code the static dependencies a explicitly stated: if we read
>> >  "use File::Temp;" at the beginning and the program is compiled successfully,
>> >  then there is a good reason to treat the module File/Temp.pm as a static
>> >  dependency.

> You've chosen a good example to prove that seemingly-static HLL
> dependancies are indeed dynamic. As I understand it, Perl 6 modules
> are not tied to the filesystem in such an intuitive way. They may be
> name-mangled or managed through a registry of some sort. "use
> File::Temp" looks up whatever your system considers to be the default
> implementation of File::Temp (there may be different versions by
> different authors). This will vary by system, and in fact needs to be
> a runtime lookup (if your bytecode is going to be able to be passed
> around between systems, robust against reconfiguration, etc).

   I used "File/Temp.pm" as a simple example of a dependency resolution. 
In fact all Perl 5 dependencies are extracted as "perl(module name)" and 
in this form are written to the package metadata. If source code 
contains "use File::Temp" then the package would automatically require 
"perl(File::Temp)" (a so called "virtual dependency" in contrast to 
"file dependency"). In attempt to install that package the 
package-management system would try to find an other package which 
provides "perl(File::Temp)". And there may be a number of such packages, 
one already installed in the target system. This "requires/provides" 
system has nothing to do with any particular module resolution method.

   So, I do not see why "use File::Temp" is not a static dependency. If 
program can not be run without that module available in the system, then 
that is a static dependency. The logic is simple.

-- 
Paul Wolneykien,
   ALT Linux, Ltd.