On 3/8/2011 12:02 PM, Terry Reedy wrote:
On 3/7/2011 9:31 PM, Reliable Domains wrote:

The launcher need not be called "python.exe", and maybe it would be
better called #@launcher.exe (or similar, depending on its exact
function details).

I do not know that the '#@' part is about, but pygo would be short and expressive.


If my proposal to make a line starting with #@ to be used instead of the Unix #! (#@ could be on the first or second line, to allow cross-platform scripts to use both, and Windows only scripts to not have #!), then #@launcher.exe (and #@launcherw.exe I suppose) would reflect the functionality of the launcher, which need not be tightly tied to Python, if it uses a separate line.  But the launcher should probably not be the thing invoked from the command line, only implicitly when running scripts by naming them as the first thing on the command line.

I'm of the opinion that attempting to parse a Unix #! line, and intuit what would be the equivalent on Windows is unnecessarily complex and error prone, and assumes that the variant systems are configured using the same guidelines (which the Python community may espouse, but may not be followed by all distributions, sysadmins, or users).  That's why I propose a different line for Windows... it is as simple as the long-proven Unix #! line, but imposes no restrictions on or requirements that there be a #! line; it has more flexibility in that it could invoke different versions or provide different options on Unix and Windows if necessary for some environments.

#!/usr/bin/env python2.6 -B
#@c:\python26\python2.6.exe

or

#!/usr/bin/python2.5
#@"C:\Program Files (x86)\IronPython 2.6 for .NET 4.0\ipy.exe"

Now that I've had this idea, one might want to create other "2nd character" codes after the Unix #! line... one could have

#! Unix command processor
#@ Windows command processor
#$ OS/2 command processor
#% Alternate Windows command processor.

One could even port it to Unix:

#!/usr/bin/#@launcher
#@c:\python2.6\python.exe
#^/usr/bin/python2.5
#&/usr/bin/mono/IronPython2.6 for .NET 4.0/ipy.exe
#  I made up the line above, having no knowledge of Mono, but I think you get the idea

Choice of command line would be an environment variable, I suppose, that the launcher would look at, or if none, then a system-specific default.  It would have to search forward in the file until it finds the appropriate prefix or a line not starting with #, or starting with "# " or "##", at which point it would give up.