On 12/04/08 19:57, Steve Hall wrote:
> On Sat, 2008-04-12 at 16:58 +0200, Bram Moolenaar wrote:
>> I would still like feedback on the format of floating point numbers:
>>
>> &123.456
>> &1.23e-3
>
> I don't understand the ampersand, why not something more mnemonic:
>
> f123.456
> .123.456
> f.123.456
> .f123.456
> +123.456
>
>
The way I see it, it's to both avoid ambiguity and avoid breaking
compatibility:
1) f123.456 is the variable f123 concatenated with the constant 456
2) .123.456 is just as arbitrary as &123.456, and maybe more ambiguous
depending what comes before. Example:
:echo foobar .123.456
doesn't mean "echo the variable foobar separated by a space from the
number one hundred twenty-three point four five six" but "echo the
variable foobar concatenated with the strings '123' and '456' (with no
spaces since it is just one expression).
3) f.123.456 is the variable f concatenated with two strings - it
amounts to f concatenated with the string '123456'
4) .f123.456 (see 2); if preceded by a string it would concatenate the
variable f123 and the string 456 to it
5) +123.456 applies the concatenation operator to two numbers so both
are converted to strings and we end up with 123456 (the string '123456',
that is).
OTOH, with & there is no ambiguity because the various uses of & are
strictly separated:
&& is the "and" logical operator. Vim (unlike C etc.) has no bitwise
operator. The use of & in 'nomagic' patterns applies only in a strictly
delimited context.
&option (where the option name always starts with a letter) is an option
used as a variable, in the LHS of the ":let" command or as all or part
of an expression.
&number (where the number always starts with + - or a digit) is a
floating-point literal.
Best regards,
Tony.
--
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