[tex-live] Make the extensions for formats different for each engine.

[Olaf Weber]

Fabrice Popineau writes:

>> Right now pdftex uses .fmt for its formats (e.g., latex.fmt) just as
>> tex does.  Similar for pdfetex and etex, which both use .efmt.  I
>> don't believe this is a desirable situation, and would like to change
>> this, possible so that

>> Thoughts?

> What's the purpose? Ensure that some tex engine won't be called with a
> format not created by the same engine? In this case it is not
> bulletproof to store the information only in the format file name. Why
> not adding a fingerprint inside the format file itself?

Mainly to help prevent accidents (like 'tex \&latex sample2e' when the
latex format is built for the pdfetex engine).  It also allows for a
degree of peaceful coexistence between formats with the same names for
different engines.

Another way to enable peaceful coexistence that has been proposed is
to separate the formats in subdirectories like this:
	texmf/web2c/tex
	texmf/web2c/etex
Each of these directories would be conform to an engine.  For that to
work best, we could have the engines define $engine like they define
$progname these days, and have something like
	TEXFORMATS = .;$TEXMF/web2c/{$engine,}//
in the texmf.cnf.

Putting a fingerprint in the format file itself is not mutually
exclusive with this.

> Fabrice

-- 
Olaf Weber

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