Re: Proposal: Syntax sugar for single exit and early exit functions.
Am 18.11.2014 um 22:03 schrieb Brendan Eich: Christian Mayer wrote: What I actually sometimes really miss in JavaScript (having a big C++ background) are destructors. (I haven't checked if they are in any new version proposal, though) No, as JS has no stack storage class, only we-hope-unobservable GC, no destructors. I fully understand that something called at GC time won't work - but that's not a real destructor for me, that would be a sort of destroyer... :) The destructor should IMHO be called when the JS internal ref count gets to 0, i.e. when the object gets released to the GC to do it's job when it wants to. (This could actually be generalized by offering a callback function that gets called every time the internal refcount gets decreased... The current ref count could be passed as a parameter then) One very obvious use case for me would be debugging and making sure that my objects aren't leaking. But anything could make sense where destructors are usually used for. ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: {Spam?} Re: Proposal: Syntax sugar for single exit and early exit functions.
Christian Mayer wrote: Am 18.11.2014 um 22:03 schrieb Brendan Eich: Christian Mayer wrote: What I actually sometimes really miss in JavaScript (having a big C++ background) are destructors. (I haven't checked if they are in any new version proposal, though) No, as JS has no stack storage class, only we-hope-unobservable GC, no destructors. I fully understand that something called at GC time won't work - but that's not a real destructor for me, that would be a sort of destroyer...:) :-D. The destructor should IMHO be called when the JS internal ref count gets to 0, i.e. when the object gets released to the GC to do it's job when it wants to. JS does not mandate reference counting, and I know of no competitive engine that uses it. /be ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Proposal: Syntax sugar for single exit and early exit functions.
Am 18.11.2014 um 06:50 schrieb Biju: Just want to add, usually in corporate world a .Net or Java developer is who code JavaScript. The code above may be little complex for them. What I actually sometimes really miss in JavaScript (having a big C++ background) are destructors. (I haven't checked if they are in any new version proposal, though) ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Proposal: Syntax sugar for single exit and early exit functions.
I have wanted something similar to this. But I think of it as having
RAII in JS.
So what I would like is:
function f() {
let x = g();
finally { x.cleanup(); }
let y = h();
finally { y.cleanup(); }
doStuff(x, y);
}
You can sort of do this with try..finally:
function f() {
let x, y;
try {
x = g();
y = h();
doStuff(x, y);
} finally {
x.cleanup();
y.cleanup();
}
}
The difference is that my 'finally' (1) may be placed directly after the
related setup code, and (2) is lexically scoped. (Also note that my
syntax suggestion probably wouldn't work, because a finally directly
after a try..catch block is ambiguous -- or would it work, because they
have identical behavior?)
As for:
function f() {
if (cond) {
finally { print(1); }
} else {
finally { print(2); }
}
}
I was kind of hoping that each finally{} could use a minimal surrounding
lexical scope (so here, the bodies of the 'if' consequents), so only one
of these finally{} blocks would run. But perhaps that's a new sort of
scope from what already exists? There could be tension between finally{}
and let scoping.
Also, in
for (var x of foo()) {
finally { print(x); }
}
I would expect the finally{} block to run on every iteration.
Could something like this fly?
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Re: {Spam?} Re: Proposal: Syntax sugar for single exit and early exit functions.
Christian Mayer wrote: Am 18.11.2014 um 06:50 schrieb Biju: Just want to add, usually in corporate world a .Net or Java developer is who code JavaScript. The code above may be little complex for them. What I actually sometimes really miss in JavaScript (having a big C++ background) are destructors. (I haven't checked if they are in any new version proposal, though) No, as JS has no stack storage class, only we-hope-unobservable GC, no destructors. /be ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Proposal: Syntax sugar for single exit and early exit functions.
I don't think we need to add any syntax sugar for the examples below.Answering with examples inline:17.11.2014, 03:07, “Biju” bijumaill...@gmail.com: I wish, I could write elegant two of the code pattern I use frequently.Patten 1.HTML button click event handler should always return false (ie, whenyou never want the submit action).So I always write.function someClickHandler(){ try {doStuff();doAnotherStuff();doYetAnotherStuff(); } catch(e){ } return false;} This is already good enough. If you want to handle exceptions, you have to add try..catch. Patten 2.I do like to code functions with early exit, likefunction someValidationProcess(){doStuff();if(condition_1()){doCleanUp_1();doCleanUp_2();}doAnotherStuff();if(condition_2()){doCleanUp_1();doCleanUp_2(); }doYetAnotherStuff();if(condition_3()){doCleanUp_1();doCleanUp_2(); }doMoreStuff();doCleanUp_1();doCleanUp_2();} If you do the same stuff after each function, some functional programming could help:function someValidationProcess() {
;[doStuff, doAnotherStuff, doYetAnotherStuff, doMoreStuff]
.forEach(function(fn) {
fn()
doCleanUp_1()
doCleanUp_2()
})
}
In this case doStuff would have to set a flag instead of condition_1() probably. Proposal:I wish there was some syntax sugar likefunction someClickHandler(){doStuff();doAnotherStuff();doYetAnotherStuff();} finally { return false;} Syntax sugar for try..catch? I don’t think we need one of those. function someValidationProcess(){doStuff();breakif(condition_1());doAnotherStuff();breakif(condition_2());doYetAnotherStuff();breakif(condition_3());doMoreStuff();} finally {doCleanUp_1();doCleanUp_2();} How about a loop?function someValidationProcess() {
do {
doStuff()
if (condition_1()) break
doAnotherStuff()
if (condition_2()) break
doYetAnotherStuff()
if (condition_3()) break
doMoreStuff()
} while(0)
doCleanUp_1()
doCleanUp_2()
}
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Re: Proposal: Syntax sugar for single exit and early exit functions.
On 17 November 2014 17:29, Alex Kocharin a...@kocharin.ru wrote:
17.11.2014, 03:07, “Biju” bijumaill...@gmail.com:
I wish, I could write elegant two of the code pattern I use frequently.
[...]
Patten 2.
I do like to code functions with early exit, like
function someValidationProcess(){
doStuff();
if(condition_1()){
doCleanUp_1();
doCleanUp_2();
}
doAnotherStuff();
if(condition_2()){
doCleanUp_1();
doCleanUp_2();
}
doYetAnotherStuff();
if(condition_3()){
doCleanUp_1();
doCleanUp_2();
}
doMoreStuff();
doCleanUp_1();
doCleanUp_2();
}
Sounds like you would like to have monad comprehension syntax. :)
How about a loop?
function someValidationProcess() {
do {
doStuff()
if (condition_1()) break
doAnotherStuff()
if (condition_2()) break
doYetAnotherStuff()
if (condition_3()) break
doMoreStuff()
} while(0)
doCleanUp_1()
doCleanUp_2()
}
No need for a fake loop:
function someValidationProcess() {
validate: {
doStuff()
if (condition_1()) break validate
doOtherStuff()
if (condition_2()) break validate
// etc.
}
doCleanUp_1()
doCleanUp_2()
}
But I'd rather use a separate function for the clean-up.
/Andreas
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Re: Proposal: Syntax sugar for single exit and early exit functions.
`validate: { ... }`
Is that an ES7 feature? I don't recognize it from ES6, and can't seem to
find a relevant proposal with that syntax...
On Mon, Nov 17, 2014 at 11:51 AM, Andreas Rossberg rossb...@google.com
wrote:
On 17 November 2014 17:29, Alex Kocharin a...@kocharin.ru wrote:
17.11.2014, 03:07, “Biju” bijumaill...@gmail.com:
I wish, I could write elegant two of the code pattern I use frequently.
[...]
Patten 2.
I do like to code functions with early exit, like
function someValidationProcess(){
doStuff();
if(condition_1()){
doCleanUp_1();
doCleanUp_2();
}
doAnotherStuff();
if(condition_2()){
doCleanUp_1();
doCleanUp_2();
}
doYetAnotherStuff();
if(condition_3()){
doCleanUp_1();
doCleanUp_2();
}
doMoreStuff();
doCleanUp_1();
doCleanUp_2();
}
Sounds like you would like to have monad comprehension syntax. :)
How about a loop?
function someValidationProcess() {
do {
doStuff()
if (condition_1()) break
doAnotherStuff()
if (condition_2()) break
doYetAnotherStuff()
if (condition_3()) break
doMoreStuff()
} while(0)
doCleanUp_1()
doCleanUp_2()
}
No need for a fake loop:
function someValidationProcess() {
validate: {
doStuff()
if (condition_1()) break validate
doOtherStuff()
if (condition_2()) break validate
// etc.
}
doCleanUp_1()
doCleanUp_2()
}
But I'd rather use a separate function for the clean-up.
/Andreas
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Re: Proposal: Syntax sugar for single exit and early exit functions.
OH JEEZ. Please ignore previous email.
On Mon, Nov 17, 2014 at 12:00 PM, Jeremy Martin jmar...@gmail.com wrote:
`validate: { ... }`
Is that an ES7 feature? I don't recognize it from ES6, and can't seem to
find a relevant proposal with that syntax...
On Mon, Nov 17, 2014 at 11:51 AM, Andreas Rossberg rossb...@google.com
wrote:
On 17 November 2014 17:29, Alex Kocharin a...@kocharin.ru wrote:
17.11.2014, 03:07, “Biju” bijumaill...@gmail.com:
I wish, I could write elegant two of the code pattern I use frequently.
[...]
Patten 2.
I do like to code functions with early exit, like
function someValidationProcess(){
doStuff();
if(condition_1()){
doCleanUp_1();
doCleanUp_2();
}
doAnotherStuff();
if(condition_2()){
doCleanUp_1();
doCleanUp_2();
}
doYetAnotherStuff();
if(condition_3()){
doCleanUp_1();
doCleanUp_2();
}
doMoreStuff();
doCleanUp_1();
doCleanUp_2();
}
Sounds like you would like to have monad comprehension syntax. :)
How about a loop?
function someValidationProcess() {
do {
doStuff()
if (condition_1()) break
doAnotherStuff()
if (condition_2()) break
doYetAnotherStuff()
if (condition_3()) break
doMoreStuff()
} while(0)
doCleanUp_1()
doCleanUp_2()
}
No need for a fake loop:
function someValidationProcess() {
validate: {
doStuff()
if (condition_1()) break validate
doOtherStuff()
if (condition_2()) break validate
// etc.
}
doCleanUp_1()
doCleanUp_2()
}
But I'd rather use a separate function for the clean-up.
/Andreas
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@jmar777
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Jeremy Martin
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@jmar777
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Re: Proposal: Syntax sugar for single exit and early exit functions.
On 17 November 2014 11:29, Alex Kocharin a...@kocharin.ru wrote:
If you do the same stuff after each function, some functional programming
could help:
function someValidationProcess() {
;[doStuff, doAnotherStuff, doYetAnotherStuff, doMoreStuff]
.forEach(function(fn) {
fn()
doCleanUp_1()
doCleanUp_2()
})
}
In this case doStuff would have to set a flag instead of condition_1()
probably.
Just want to add, usually in corporate world a .Net or Java developer
is who code JavaScript. The code above may be little complex for them.
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Re: Proposal: Syntax sugar for single exit and early exit functions.
On 11/16/14, Biju bijumaill...@gmail.com wrote:
[...]
Proposal:
I wish there was some syntax sugar like
function someClickHandler(){
doStuff();
doAnotherStuff();
doYetAnotherStuff();
} finally {
return false;
}
function rf() {
try {
throw-an-error;
} finally {
return false;
}
}
rf(); // false
--
Garrett
@xkit
ChordCycles.com
garretts.github.io
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Re: Proposal: Syntax sugar for single exit and early exit functions.
Returning false isn't the common way to prevent the default action anymore,
event.preventDefault() is. In that case you'd just preventDefault at the
top of your function.
The other use cases can be satisfied with simple high order functions like
andReturn(f, x) or compose(f, g).
On Sun, Nov 16, 2014 at 5:07 PM, Biju bijumaill...@gmail.com wrote:
I wish, I could write elegant two of the code pattern I use frequently.
Patten 1.
HTML button click event handler should always return false (ie, when
you never want the submit action).
So I always write.
function someClickHandler(){
try {
doStuff();
doAnotherStuff();
doYetAnotherStuff();
} catch(e){
}
return false;
}
Patten 2.
I do like to code functions with early exit, like
function someValidationProcess(){
doStuff();
if(condition_1()){
doCleanUp_1();
doCleanUp_2();
}
doAnotherStuff();
if(condition_2()){
doCleanUp_1();
doCleanUp_2();
}
doYetAnotherStuff();
if(condition_3()){
doCleanUp_1();
doCleanUp_2();
}
doMoreStuff();
doCleanUp_1();
doCleanUp_2();
}
Proposal:
I wish there was some syntax sugar like
function someClickHandler(){
doStuff();
doAnotherStuff();
doYetAnotherStuff();
} finally {
return false;
}
function someValidationProcess(){
doStuff();
breakif(condition_1());
doAnotherStuff();
breakif(condition_2());
doYetAnotherStuff();
breakif(condition_3());
doMoreStuff();
} finally {
doCleanUp_1();
doCleanUp_2();
}
Cheers
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