Looks like calling .bind(this) on any generator function breaks my ability to see if the function is a generator. Any ideas on how to fix this?
var isGenerator = function(fn) {
if(!fn) {
return false;
}
var isGenerator = false;
// Faster method first
// Calling .bind(this) causes fn.constructor.name to be 'Function'
if(fn.constructor.name === 'GeneratorFunction') {
isGenerator = true;
}
// Slower method second
// Calling .bind(this) causes this test to fail
else if(/^function\s*\*/.test(fn.toString())) {
isGenerator = true;
}
return isGenerator;
}
var myGenerator = function*() {
}
var myBoundGenerator = myGenerator.bind(this);
isGenerator(myBoundGenerator); // false, should be true
A generator function is a function with one or more yield statements in it. Unlike regular functions, generator functions return generator objects. Meaning, when you call a generator function, it doesn't run the function.
Create Generators in PythonIf a function contains at least one yield statement (it may contain other yield or return statements), it becomes a generator function. Both yield and return will return some value from a function.
Calling a generator function does not execute its body immediately; a generator object for the function is returned instead.
// Declare a generator function with a single return value function* generatorFunction() { return 'Hello, Generator!' } The Generator object returned by the function is an iterator. An iterator is an object that has a next() method available, which is used for iterating through a sequence of values.
Since .bind()
returns a new (stub) function that only just calls the original with .apply()
in order to attach the proper this
value, it is obviously no longer your generator and that is the source of your issue.
There is a solution in this node module: https://www.npmjs.org/package/generator-bind.
You can either use that module as is or see how they solve it (basically they make the new function that .bind()
returns also be a generator).
Yes, it is possible to tell if a function is a generator even if .bind() has been called on it:
function testIsGen(f) {
return Object.getPrototypeOf(f) === Object.getPrototypeOf(function*() {});
}
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