Re: a question about `,' in backquote

[Andreas Schwab]

Masatake YAMATO <address@hidden> writes:

> I found a following line in the definition of `tags-search':
>
>    (setq tags-loop-scan `(re-search-forward ',regexp nil t)
>
> Could you tell me why "'" is needed before "," ?

Because the form is passed to eval, which evaluates the function arguments
before applying them.  Thus without the quote it would effectively be
doing (eval regexp), which is not what is wanted.  Of course, the only
valid type of this argument is a string which is self-evaluating, but you
don't want to evaluate arbitrary values in the error case.

Andreas.

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Andreas Schwab, SuSE Labs, address@hidden
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