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The problem is that all the "do what I mean" examples become part of the spec, and then have to be supported forever. Whereas "prints an extra-informative error

The problem is that all the "do what I mean" examples become part of the spec, and then have to be supported forever. Whereas "prints an extra-informative error" is much easier to change. Even for low hanging fruit. eg, `exit` in Python can be redefined as a variable - so if I do that and then type `exit`, should it print that value for me or quit the REPL? Is it better to guess, or just not encourage the user to do the wrong thing? If I make `-?` print help, what happens when I want to define `-` as "read the following text as input" and then users start getting bizarre behavior instead of the help file? You can probably come up with ever-fancier ways to work around this, but that takes effort, and more testing, and more code...

Hizonner 3y ago
> If I make `-?` print help, what happens when I want to define `-` as "read the following text as input" and then users start getting bizarre behavior instead of the help file? I'm not sure what that means, but if you're saying that you would want your program to interpret "-?" as though somebody had run it with no option at all and then provided a question mark on the standard input, that's really obnoxious and grounds for torches and pitchforks from all users. Look, on a command line, a bare hyphen, given as an argument where there might otherwise be a filename, can reasonably mean "read from the standard input" or "write to the standard output", but only because it's been so common for so long. As an alternative to it, you can just use standard input/output by default, or you can just punt and make the user give you something like "/dev/stdin". In any other context, a hyphen introduces an option that modifies normal program behavior. If it's a single hyphen, then the option name is a single character. If it's a double hyphen, the option name is the rest of the argument up to any equal sign. It should consist of complete words and be in `kebab-case`, not `snake_case`. But even if you violate those rules, it's a far more basic rule that an argument starting with a hyphen is an OPTION NAME, not arbitrary data. And the options "-h", "--help", and I guess maybe "-?" and "--?" are pretty much universally used to mean "print help about how to use your program". Changing that is insane. I know that code on on Windows does horrific stuff (including pretending it's freaking RSX-11 and using slashes of all things). I know that some really old UNIX stuff written in the bad old days also breaks the rules. But even those don't just arbitrarily redefine what the hyphen means. Redefining absolutely everything under the user, to the point where they can't even guess how to ask for help, is just crazy.

Hizonner 3y ago

> If I make `-?` print help, what happens when I want to define `-` as "read the following text as input" and then users start getting bizarre behavior instead of the help file? I'm not sure what that means, but if you're saying that you would want your program to interpret "-?" as though somebody had run it with no option at all and then provided a question mark on the standard input, that's really obnoxious and grounds for torches and pitchforks from all users. Look, on a command line, a bare hyphen, given as an argument where there might otherwise be a filename, can reasonably mean "read from the standard input" or "write to the standard output", but only because it's been so common for so long. As an alternative to it, you can just use standard input/output by default, or you can just punt and make the user give you something like "/dev/stdin". In any other context, a hyphen introduces an option that modifies normal program behavior. If it's a single hyphen, then the option name is a single character. If it's a double hyphen, the option name is the rest of the argument up to any equal sign. It should consist of complete words and be in `kebab-case`, not `snake_case`. But even if you violate those rules, it's a far more basic rule that an argument starting with a hyphen is an OPTION NAME, not arbitrary data. And the options "-h", "--help", and I guess maybe "-?" and "--?" are pretty much universally used to mean "print help about how to use your program". Changing that is insane. I know that code on on Windows does horrific stuff (including pretending it's freaking RSX-11 and using slashes of all things). I know that some really old UNIX stuff written in the bad old days also breaks the rules. But even those don't just arbitrarily redefine what the hyphen means. Redefining absolutely everything under the user, to the point where they can't even guess how to ask for help, is just crazy.