Add a hint suggesting to use ( * ) when (*) is used

[Armael]

A common rookie mistake is to write (*), trying to get the prefix equivalent of the multiplication function -- the compiler rightfully warns that this is in fact the beginning of a comment, but does not explain how to actually get the prefix version.

This patch simply extends the existing warning in order to suggest using ( * ) instead.

[Octachron]

Would it not be a bit clearer to precise that ( * ) is an operator: Did you mean the operator `( * )'? ?

[Armael]

Good point!

[gasche]

Why not be fully explicit, "the infix operator ( * ) for multiplication"?

[Armael]

Indeed. Patch updated.

[Octachron]

Some weak counter-arguments

• infix: ( * )cannot be used in infix position
• for multiplication: some misguided people use * for vector product, others may not spontaneously associate convolution ( which is the natural * with distributions ) with *

But I agree that the infix operator ( * ) for multiplication is fine overall

[gasche]

I apologize for the bike-shedding, but I think that "(* is the start of a comment" would be a better first line (than "this"). Then for the hint, one possibility (but I'm not sure it is an improvement) would be to say "Hint: If you meant to write the infix operator ( * ) for multiplication, you should add spaces within the parentheses."

[Octachron]

Maybe This "(* is the start of a comment to avoid starting a sentence with a symbol?

Also, going beyond one line of hint in

Hint: If you meant to write the infix operator ( * ) for multiplication, you should add spaces within the parentheses.

feels a bit verbose.

[gasche]

Yep, "This (*" is nice. I think that it is good to be a bit demonstrative.

For the second sentence, my idea was to say explicitly "you need to add spaces", but if there is no space (sic) for this maybe just showing the symbol without a space above and the symbol with spaces below is enough.

[Octachron]

Then maybe we should put the focus on the actual human mistake:
Did you forget spaces when writing the infix operator `( * )`
(with optionally for multiplication)

[gasche]

Excellent!

[Armael]

Thanks for the discussion. I just amended the patch.

[gasche]

(Why are you using double-backtick in the first line, and backtick-singlequote in the second line?)

[Armael]

(Oops, fixed)

[damiendoligez]

Just a remark for next time: backtick and single quote are not a pair of matched quotation marks, so you shouln't use them in this way. The problem is rather well explained in this page: http://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html