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I also am confused by using the Pyramid of Doom as a pseudo rationale for needing this. Pyramid too tall? Use a function call. Nothing at all wrong with: f

I also am confused by using the Pyramid of Doom as a pseudo rationale for needing this. Pyramid too tall? Use a function call. Nothing at all wrong with: function multiStepAsyncProcess() { hitServer(params, function() { multiStepAsyncProcessStep2(); }); } function multiStepAsyncProcessStep2() { hitServer(params, function() { ... }); }

rmrfrmrf 9y ago
Now do it with error handling and recovery.
- xg15 9y ago
  Moreover, async/await allows you to preserve multiple intermediary results between async steps - which is awkward in both promises and un-nested pyramids like the OP's: (not even starting with conditions, loops and recursive calls that contain async steps...) Async/Await: async function f(a) { var b = await foo(a); var c = await bar(a, b); return baz(a, b, c); } Promises: function f(a) { var _b; return foo(a) .then(b => { _b = b; return bar(a, b); }) .then(c => baz(a, _b, c)) } Callbacks: function f(a, done) { foo(a, b => bar(a, b, c => baz(a, b, c, done))); } Callbacks untangled: function f(a, done) { var _b; foo(a, step2); function step2(b) { _b = b; bar(a, b, step3); } function step3(c) { baz(a, _b, c, done); } }
- CodeWriter23 9y ago
  <shrugs> ok function multiStepAsyncProcess() { hitServer(params, function(err) { if(err) { handleError(err); return; } multiStepAsyncProcessStep2(); }); } function multiStepAsyncProcessStep2() { hitServer(params, function(err) { ... }); }
always_good 9y ago
That just "fixes it" with indirection, which is the only tool you have with callback style.
- CodeWriter23 9y ago
  Actually I characterize it as opting out of newly-introduced madness, and using the techniques we used pre-madness. Not a “fix” so much.
  - always_good 9y ago
    I can agree with that. I think the problem with these sorts of discussions starts when someone dismisses promises, at which point one must assume that the person dismisses the problems that promises solve. And I think that happens in the other direction too, when someone dismisses callbacks which suggests that they think that callbacks are intractable in all scenarios.

rmrfrmrf 9y ago

Now do it with error handling and recovery.

xg15 9y ago
Moreover, async/await allows you to preserve multiple intermediary results between async steps - which is awkward in both promises and un-nested pyramids like the OP's: (not even starting with conditions, loops and recursive calls that contain async steps...) Async/Await: async function f(a) { var b = await foo(a); var c = await bar(a, b); return baz(a, b, c); } Promises: function f(a) { var _b; return foo(a) .then(b => { _b = b; return bar(a, b); }) .then(c => baz(a, _b, c)) } Callbacks: function f(a, done) { foo(a, b => bar(a, b, c => baz(a, b, c, done))); } Callbacks untangled: function f(a, done) { var _b; foo(a, step2); function step2(b) { _b = b; bar(a, b, step3); } function step3(c) { baz(a, _b, c, done); } }
CodeWriter23 9y ago
<shrugs> ok function multiStepAsyncProcess() { hitServer(params, function(err) { if(err) { handleError(err); return; } multiStepAsyncProcessStep2(); }); } function multiStepAsyncProcessStep2() { hitServer(params, function(err) { ... }); }

always_good 9y ago

That just "fixes it" with indirection, which is the only tool you have with callback style.

CodeWriter23 9y ago
Actually I characterize it as opting out of newly-introduced madness, and using the techniques we used pre-madness. Not a “fix” so much.
- always_good 9y ago
  I can agree with that. I think the problem with these sorts of discussions starts when someone dismisses promises, at which point one must assume that the person dismisses the problems that promises solve. And I think that happens in the other direction too, when someone dismisses callbacks which suggests that they think that callbacks are intractable in all scenarios.