I'm developing a language which I intend to replace both Javascript and PHP. (I can't see any problem with this. It's not like either of these languages have a large install base.)One of the things I wanted to change was to turn the assignment operator into an assignment command, removing the ability to make use of the returned value.x=1;          /* Assignment. */if (x==1) {}  /* Comparison. */x==1;         /* Error or warning, I've not decided yet. */if (x=1) {}   /* Error. */I know that this would mean that those one-line functions that C people love so much would no longer work. I figured (with little evidence beyond my personal experience) that the vast majority of times this happened, it was really intended to be comparison operation.Or is it? Are there any practical uses of the assignment operator's return value that could not be trivially rewritten? (For any language that has such a concept.)
What is the benefit of having the assignment operator return a value?
language agnostic;syntax;operators
Technically, some syntactic sugar can be worth keeping even if it can trivially be replaced, if it improves readability of some common operation.But assignment-as-expression does not fall under that. The danger of typo-ing it in place of a comparison means it's rarely used (sometimes even prohibited by style guides) and provokes a double take whenever it is used. In other words, the readability benefits are small in number and magnitude.A look at existing languages that do this may be worthwhile.Java and C# keep assignment an expression but remove the pitfall you mention by requiring conditions to evaluate to booleans. This mostly seems to work well, though people occasionally complain that this disallows conditions like if (x) in place of if (x != null) or if (x != 0) depending on the type of x.Python makes assignment a proper statement instead of an expression. Proposals for changing this occasionally reach the python-ideas mailing list, but my subjective impression is that this happens more rarely and generates less noise each time compared to other missing features like do-while loops, switch statements, multi-line lambdas, etc.However, Python allows one special case, assigning to multiple names at once: a = b = c. This is considered a statement equivalent to b = c; a = b, and it's occasionally used, so it may be worth adding to your language as well (but I wouldn't sweat it, since this addition should be backwards-compatible).