Re: [Pharo-users] Why no collect:ifNone: ?

[Tim Mackinnon]

You can learn so much from these innocent questions Maximiliano pointed out 
that there is a difference between #sum and a method I never noticed 
#sumNumbers, the latter would avoided my problem too...

Sent from my iPhone

> On 30 Apr 2018, at 23:00, Tim Mackinnon  wrote:
> 
> Yep - as I was reading the replies from you and Esteban - I was thinking 
> there was something odd, and its correct, I’ve been careless - the 
> problematic code had a trailing #sum to it, which is actually where the 
> problem was…. 
> 
> total := schedule ifEmpty: [ 0 ] ifNotEmpty: [ :c |
>(c collect: [ :r | ((DateAndTime fromString: r end) - (DateAndTime 
> fromString: r start)) asHours ]) sum ].
> 
> So you are both correct - it should have used inject.
> 
> total := schedule inject: 0 into: [ :result :item | result + ((DateAndTime 
> fromString: item end) - (DateAndTime fromString: item start)) asHours ].
> 
> Oops - thanks for being my sound board.
> 
> Tim 
> 
>> On 30 Apr 2018, at 22:02, Francisco Garau  wrote:
>> 
>> 
>> Have you tried #inject:into: ? Looks like what are needing here 
>> 
>> - Francisco
>> 
>> 
>>> On 30 Apr 2018, at 19:37, Tim Mackinnon  wrote:
>>> 
>>> 
>>> Hi - I hit a small bug in my lunch experiments with Willow where I wanted 
>>> to sum up a collection of support hours.
>>> 
>>> I was collect: in the hours worked and hadn’t accounted for an empty 
>>> collection.
>>> 
>>> When I went to do it I was surprised there isn’t a concept of 
>>> #collect:ifNone: that mirrors something like at:ifAbsent: or the nicely 
>>> readable collect:thenXxx: methods.
>>> 
>>> Why is this?
>>> 
>>> I’m curious about style - and the elegance of my workaround :
>>> 
>>> result ifEmpty: [ 0 ] ifNotEmpty:[ :r | r collect: [:I | i hours ]]
>>> 
>>> which is ok, but seems a mouthful?
>>> 
>>> Am I missing a trick?
>>> 
>>> Tim
>>> 
>>> Sent from my iPhone
>>> 
> 
> 

Re: [Pharo-users] Why no collect:ifNone: ?

[Tim Mackinnon]

Yep - as I was reading the replies from you and Esteban - I was thinking there 
was something odd, and its correct, I’ve been careless - the problematic code 
had a trailing #sum to it, which is actually where the problem was…. 

total := schedule ifEmpty: [ 0 ] ifNotEmpty: [ :c |
(c collect: [ :r | ((DateAndTime fromString: r end) - 
(DateAndTime fromString: r start)) asHours ]) sum ].

So you are both correct - it should have used inject.

total := schedule inject: 0 into: [ :result :item | result + ((DateAndTime 
fromString: item end) - (DateAndTime fromString: item start)) asHours ].

Oops - thanks for being my sound board.

Tim 

> On 30 Apr 2018, at 22:02, Francisco Garau  wrote:
> 
> 
> Have you tried #inject:into: ? Looks like what are needing here 
> 
> - Francisco
> 
> 
>> On 30 Apr 2018, at 19:37, Tim Mackinnon  wrote:
>> 
>> 
>> Hi - I hit a small bug in my lunch experiments with Willow where I wanted to 
>> sum up a collection of support hours.
>> 
>> I was collect: in the hours worked and hadn’t accounted for an empty 
>> collection.
>> 
>> When I went to do it I was surprised there isn’t a concept of 
>> #collect:ifNone: that mirrors something like at:ifAbsent: or the nicely 
>> readable collect:thenXxx: methods.
>> 
>> Why is this?
>> 
>> I’m curious about style - and the elegance of my workaround :
>> 
>> result ifEmpty: [ 0 ] ifNotEmpty:[ :r | r collect: [:I | i hours ]]
>> 
>> which is ok, but seems a mouthful?
>> 
>> Am I missing a trick?
>> 
>> Tim
>> 
>> Sent from my iPhone
>> 

Re: [Pharo-users] Why no collect:ifNone: ?

[Esteban A. Maringolo]

Hi Tim,

What I found confusing there is that with #select:thenCollect: or
#collect:thenXxx: you're always dealing with collections.

In your #collect:ifNone: there is a mix. You can return a collection
(#collect:) or the result of evaluating the emptyBlock, which in your
example is a number, so I it seems like a semantic mismatch smell to me.

Following your example:

myVar := result ifEmpty: [ 0 ] ifNotEmpty:[ :r | r collect: [:I | i
hours ]].

What will be in myVar? a collection? a number? something else?.

Maybe your example is too abstract to give a good feedback.

Regards,



On 30/04/2018 15:37, Tim Mackinnon wrote:
> 
> Hi - I hit a small bug in my lunch experiments with Willow where I wanted to 
> sum up a collection of support hours.
> 
> I was collect: in the hours worked and hadn’t accounted for an empty 
> collection.
> 
> When I went to do it I was surprised there isn’t a concept of 
> #collect:ifNone: that mirrors something like at:ifAbsent: or the nicely 
> readable collect:thenXxx: methods.
> 
> Why is this?
> 
> I’m curious about style - and the elegance of my workaround :
> 
> result ifEmpty: [ 0 ] ifNotEmpty:[ :r | r collect: [:I | i hours ]]
> 
> which is ok, but seems a mouthful?
> 
> Am I missing a trick?
> 
> Tim
> 
> Sent from my iPhone
> 

-- 
Esteban A. Maringolo

[Pharo-users] Why no collect:ifNone: ?

[Tim Mackinnon]

Hi - I hit a small bug in my lunch experiments with Willow where I wanted to 
sum up a collection of support hours.

I was collect: in the hours worked and hadn’t accounted for an empty collection.

When I went to do it I was surprised there isn’t a concept of #collect:ifNone: 
that mirrors something like at:ifAbsent: or the nicely readable 
collect:thenXxx: methods.

Why is this?

I’m curious about style - and the elegance of my workaround :

result ifEmpty: [ 0 ] ifNotEmpty:[ :r | r collect: [:I | i hours ]]

which is ok, but seems a mouthful?

Am I missing a trick?

Tim

Sent from my iPhone