suffix alias

suffix alias

[Thorsten Kampe]

Hi,

I have a suffix alias "alias -s py=python". Now I can execute Python 
scripts by name that don't have a "she-bang" and aren't executable. 
That's great.

But now I noticed that I cannot execute Python scripts anymore that 
are placed in my path (/usr/bin for example) because zsh doesn't 
search the path anymore for the suffix alias.

Is there a solution for this problem?

Thorsten
-- 
For instance:
thorsten@cathedral% pwd
/home/thorsten
thorsten@cathedral% rst2html.py --version
python: can't open file 'rst2html.py'
thorsten@cathedral% unalias -s py
thorsten@cathedral% rst2html.py --version
rst2html.py (Docutils 0.3.6)

That's right - 'rst2html.py' isn't in the current working directory 
but in /usr/bin where the install put it.

Re: suffix alias

[Peter Stephenson]

Thorsten Kampe wrote:
> Hi,
> 
> I have a suffix alias "alias -s py=python". Now I can execute Python 
> scripts by name that don't have a "she-bang" and aren't executable. 
> That's great.
> 
> But now I noticed that I cannot execute Python scripts anymore that 
> are placed in my path (/usr/bin for example) because zsh doesn't 
> search the path anymore for the suffix alias.
> 
> Is there a solution for this problem?

exec-py () {
        local -a files
        files=(${^path}/$1(N))
        (( ${#files} )) && set -- $files[1] "${(@)argv[2,-1]}"
        python "$@"
}
alias -s py=exec-py

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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Re: suffix alias

[Thorsten Kampe]

* Peter Stephenson (2004-11-11 15:50 +0100)
> Thorsten Kampe wrote:
>> I have a suffix alias "alias -s py=python". Now I can execute Python 
>> scripts by name that don't have a "she-bang" and aren't executable. 
>> That's great.
>> 
>> But now I noticed that I cannot execute Python scripts anymore that 
>> are placed in my path (/usr/bin for example) because zsh doesn't 
>> search the path anymore for the suffix alias.
>> 
>> Is there a solution for this problem?
> 
> exec-py () {
>         local -a files
>         files=(${^path}/$1(N))
>         (( ${#files} )) && set -- $files[1] "${(@)argv[2,-1]}"
>         python "$@"
> }
> alias -s py=exec-py

Thanks. So there is no "builtin" solution for this. I thought of
"command rst2html.py" which is a "kind of solution", too.

Could you explain a bit what your wrapping function does?

Thorsten

Re: suffix alias

[Peter Stephenson]

Thorsten Kampe wrote:
> 
> Thanks. So there is no "builtin" solution for this. I thought of
> "command rst2html.py" which is a "kind of solution", too.

Generally speaking, shell functions are more flexible.  There's no real
gain from adding some kind of builtin support in a case like this.
Where you would need an internal change is if you wanted to match
files by patterns rather than suffixes.

> Could you explain a bit what your wrapping function does?

I thought someone might ask.

exec-py () {
  # Collect matches in local array files.  There might
  # be more than one match in $path.
  local -a files
  # This is a very common trick in zsh for searching paths.
  # ${^path}/$1 becomes $path[1]/$1 $path[2]/$1 ...
  # i.e. trial matches that might or might not be real files.
  # The (N) qualifier removes any elements that don't correspond to files.
  files=(${^path}/$1(N))
  # If we found a file, replace $1 by the path to the first match,
  # i.e. the earliest in the $path.
  # If we didn't find the file in path, leave the arguments alone.
  # A simpler version would be:
  #   (( ${#files} )) && 1=$files[1]
  (( ${#files} )) && set -- $files[1] "${(@)argv[2,-1]}"
  # Execute python with the original command line except with
  # $1 replaced as above.
  python "$@"
}
# Use the function instead of python for .py files.
alias -s py=exec-py

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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