digitalmars.D - Re: Number literals (Was: Re: Case Range Statement ..)
- bearophile <bearophileHUGS lycos.com> Jul 08 2009
- Don <nospam nospam.com> Jul 08 2009
Walter Bright:Not a significant issue, as the code to lex it is done, works, and is readily available.
It's not an issue for the compiler, but a modern programming language has to be designed for programmers, to be as little bug-prone as possible. Literals as .5 and 5. are not correct in my natural language, they look ugly, and they are a bit dangerous. That's why I think it's better to disallow them.Translating C code to D.<
The main problem is turning a literal like 0555 into a syntax error, but failing silently or giving a different answer. Now in Python 3+ literals like 0720 are disallowed, you have to use 0o720 instead. I was one of the people that have suggested and voted for this change. It's one of the few changes in Python that come from a suggestion of mine. Regarding Python 3, it contains a single built-in module that's named 2to3, it's not too much long and it's quite useful: http://docs.python.org/library/2to3.html I think that writing a similar standard and built-in Python module to translate C/H code to D can be positive. Then all D distributions can contain it. Among the things it does it to reformat code and convert C octals to D octals :-) Bye, bearophile
Jul 08 2009
bearophile wrote:Walter Bright:Not a significant issue, as the code to lex it is done, works, and is readily available.
It's not an issue for the compiler, but a modern programming language has to be designed for programmers, to be as little bug-prone as possible. Literals as .5 and 5. are not correct in my natural language, they look ugly, and they are a bit dangerous. That's why I think it's better to disallow them.Translating C code to D.<
The main problem is turning a literal like 0555 into a syntax error, but failing silently or giving a different answer.
Now in Python 3+ literals like 0720 are disallowed, you have to use 0o720 instead. I was one of the people that have suggested and voted for this change. It's one of the few changes in Python that come from a suggestion of mine. Regarding Python 3, it contains a single built-in module that's named 2to3, it's not too much long and it's quite useful: http://docs.python.org/library/2to3.html I think that writing a similar standard and built-in Python module to translate C/H code to D can be positive. Then all D distributions can contain it. Among the things it does it to reformat code and convert C octals to D octals :-) Bye, bearophile
Just make a CTFE function for converting an octal string to an int. T octalLiteral(T=int)(string s) { T r=0; foreach(c; s) { assert(c>='0' && c<='7', "Invalid character in octal literal"); r *= 8; r += (c-'0'); } return r; } static assert(octalLiteral("012")==012); static assert(octalLiteral("0716")==0716); static assert(octalLiteral!(long)("071625636464")==071625636464L); Why do we need language support for something which is so obscure and can be so trivially implemented in a library? (Note that it's only possible because of CTFE).
Jul 08 2009