4 ms·

Isn't that common for all/most languages that don't require explicit typing?

samhw 5y ago
It would be impossible in any language that requires either explicit typing or some kind of 'let' keyword. (Or, in the fringe case, a language like Go which uses a different operator for initialisation-plus-assignment.)
- voltagedivider 5y ago
  Exactly. That's why I asked about languages that don't require explicit typing. My point is that it's a feature of many languages rather than a Python idiosyncrasy.
xigoi 5y ago
JavaScript (strict mode) doesn't have explicit typing, but it still requires variables to be declared.
- wott 5y ago
  Same for Perl.
  - renox 5y ago
    Uh? Perl optionally requires you to declare variables, which is a good idea IMHO, no noise for small script and any experimented Perl programmer will have learned that 'use strict' is a really good idea for big scripts..
dragonwriter 5y ago
Declaration and explicit typing are logically orthogonal, but few if any languages require typing but not declaration. Lots require declaration but not typing.
wruza 5y ago
This is a scoping rule, not typing. Scoping is a mechanism of symbol resolution, i.e. what do you mean by `foo` at line N. Is it a local, an argument, a global, or addresses a symbol defined in an enclosing scope? Most languages use explicit local definitions, searching implicit ones in outer scopes bottom-up, ending at the global scope. Python was the first popular non-basic language which made implicit assignments to be local and shadowing and function-scoped: global x = 1 def setx(): if True: x = 2 # completely different x print x # prints 2, visible outside of `if` setx() print x # prints 1 This led to a funny keyword 'nonlocal', because you can't simply ignore scoping and pretend that you're BASIC in any serious program. (To my opinion, python had a good start, but lost in the woods for no clear reason. It's a movie mutant of a language, which tried to appeal to non-programmers and somehow succeed, and then realized that non-programmers eventually become ones, and it's not hard. Now it's too late to fix this mess. End of opinion.)
bjoli 5y ago
It is common tonall languages that have the same syntax for definitions and mutation. In Scheme, for example, this is not an issue.

It would be impossible in any language that requires either explicit typing or some kind of 'let' keyword. (Or, in the fringe case, a language like Go which uses a different operator for initialisation-plus-assignment.)

voltagedivider 5y ago
Exactly. That's why I asked about languages that don't require explicit typing. My point is that it's a feature of many languages rather than a Python idiosyncrasy.

xigoi 5y ago

JavaScript (strict mode) doesn't have explicit typing, but it still requires variables to be declared.

wott 5y ago
Same for Perl.
- renox 5y ago
  Uh? Perl optionally requires you to declare variables, which is a good idea IMHO, no noise for small script and any experimented Perl programmer will have learned that 'use strict' is a really good idea for big scripts..

dragonwriter 5y ago

Declaration and explicit typing are logically orthogonal, but few if any languages require typing but not declaration. Lots require declaration but not typing.

wruza 5y ago

This is a scoping rule, not typing. Scoping is a mechanism of symbol resolution, i.e. what do you mean by `foo` at line N. Is it a local, an argument, a global, or addresses a symbol defined in an enclosing scope? Most languages use explicit local definitions, searching implicit ones in outer scopes bottom-up, ending at the global scope. Python was the first popular non-basic language which made implicit assignments to be local and shadowing and function-scoped: global x = 1 def setx(): if True: x = 2 # completely different x print x # prints 2, visible outside of `if` setx() print x # prints 1 This led to a funny keyword 'nonlocal', because you can't simply ignore scoping and pretend that you're BASIC in any serious program. (To my opinion, python had a good start, but lost in the woods for no clear reason. It's a movie mutant of a language, which tried to appeal to non-programmers and somehow succeed, and then realized that non-programmers eventually become ones, and it's not hard. Now it's too late to fix this mess. End of opinion.)

bjoli 5y ago

It is common tonall languages that have the same syntax for definitions and mutation. In Scheme, for example, this is not an issue.