Soak operations should allow undeclared variables #801

alangpierce · 2017-02-06T03:43:43Z

decaffeinate is producing the wrong JavaScript based on my CoffeeScript input:

cs = window?.CoffeeScript

(repl)

I get this output:

let cs = __guard__(window, x => x.CoffeeScript);
function __guard__(value, transform) {
  return (typeof value !== 'undefined' && value !== null) ? transform(value) : undefined;
}

Here's what I expect it to be instead:

let cs = typeof window !== "undefined" && window !== null ? window.CoffeeScript : undefined;

I think that this only happens with identifiers, and identifiers are always repeatable, so it should be reasonable to skip the __guard__ call in this case.

https://github.com/clutchski/coffeelint/blob/master/src/cache.coffee#L6

The text was updated successfully, but these errors were encountered:

Progress toward decaffeinate#801 Progress toward decaffeinate#336 Now, with a simple soak expression like `a?.b`, it will be expanded into a ternary rather than using the `__guard__` function. This allows us to handle the case where the variable is unbound (in which case the code should return `undefined` rather than throwing an exception). More specifically, we use the conditional form of soak operations As described in decaffeinate#336, I separate the expression and statement cases and prefer to wrap in an `if` if possible. This only handles the case for normal soaked member access; a later commit will expand it to soaked dynamic member access and soaked function application. Also fix a subtle bug in repeatable expression patching where a paren could be misplaced.

Progress toward #801 Progress toward #336 Now, with a simple soak expression like `a?.b`, it will be expanded into a ternary rather than using the `__guard__` function. This allows us to handle the case where the variable is unbound (in which case the code should return `undefined` rather than throwing an exception). More specifically, we use the conditional form of soak operations As described in #336, I separate the expression and statement cases and prefer to wrap in an `if` if possible. This only handles the case for normal soaked member access; a later commit will expand it to soaked dynamic member access and soaked function application. Also fix a subtle bug in repeatable expression patching where a paren could be misplaced.

Fixes decaffeinate#801 Progress toward decaffeinate#336 We now use a conditional for soaked dynamic member access and soaked function calls as long as the expression is repeatable and does not contain any soak operations. This is pretty much the same strategy as for soaked member accesses. For function calls, the code naturally becomes method call syntax when necessary, so we don't need a special case for methods like with the `__guardMethod__` stuff. There's some duplicated code, but a lot of helper methods have been shared and there are enough differences that it seems reasonable to have the duplication for now and try to consolidate later if it becomes a bigger issue.

Fixes #801 Progress toward #336 We now use a conditional for soaked dynamic member access and soaked function calls as long as the expression is repeatable and does not contain any soak operations. This is pretty much the same strategy as for soaked member accesses. For function calls, the code naturally becomes method call syntax when necessary, so we don't need a special case for methods like with the `__guardMethod__` stuff. There's some duplicated code, but a lot of helper methods have been shared and there are enough differences that it seems reasonable to have the duplication for now and try to consolidate later if it becomes a bigger issue.

alangpierce added the incorrect-output label Feb 6, 2017

alangpierce self-assigned this Feb 6, 2017

alangpierce changed the title ~~Guard operations should allow undeclared variables~~ Soak operations should allow undeclared variables Feb 10, 2017

alangpierce mentioned this issue Feb 15, 2017

Fully convert coffeelint example repo to JavaScript #823

Closed

alangpierce mentioned this issue Feb 18, 2017

feat: avoid the guard helper in some soaked member accesses #832

Merged

alangpierce mentioned this issue Feb 19, 2017

feat: avoid the guard helper in some additional soak cases #833

Merged

alangpierce closed this as completed in #833 Feb 19, 2017

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Soak operations should allow undeclared variables #801

Soak operations should allow undeclared variables #801

alangpierce commented Feb 6, 2017

Soak operations should allow undeclared variables #801

Soak operations should allow undeclared variables #801

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alangpierce commented Feb 6, 2017