Sometimes I think I don’t learn anything from my mistakes. Everytime I write a new rubygem, at first my executable doesn’t do anything no matter what commandline parameter I set etc. The reason is quite simple: Since I do a lot of Python scripting to basically every executable looks like this for me:
if __FILE__ == $0 # ... code ... end
This normally a good way to get a section of the script to be only executed when the file itself is called and not as part of a library inclusion. The problem is now, that if you’re doing this with a rubygem executable it won’t work. Rubygem automatically creates a wrapper script for each executable somewhere in your path (for example /usr/bin). Above comparision would now look like this:
if "/usr/lib/ruby/gems/1.8/gems/mygem-1.0.0/bin/mygem_exec" == "/usr/bin/mygem_exec" # ... code ... end
… which obviously can’t work ;) So just as a small reminder esp. to myself: You don’t need this check inside a rubygem since rubygems does the checking for you and you split the executable into a separated file anyway ;)
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