Define an access by key ( structure[key] ) for a custom structure struct?
$begingroup$
I have some "complicated" data that I want to encapsulate into a "struct":
For instance (imagine that data have several fields):
data=<|"A"->6,"B"->2|>
var=myType[data]
The advantage is that it is easy to filter your arguments:
doSomething[myType[d_]]:=d
(* usage: *)
doSomething[var]
Now I want to allow this:
var["B"] <- must return 2
But I do not know how to do that, any idea?
What I have done so far:
myType /: Key[k_][myType[d_]:=d[k]
This works for syntax like:
Key["B"][var]
but not for
var["B"]
associations
asked yesterday
Picaud VincentPicaud Vincent
1,065517
$endgroup$
add a comment |
$begingroup$
I have some "complicated" data that I want to encapsulate into a "struct":
For instance (imagine that data have several fields):
data=<|"A"->6,"B"->2|>
var=myType[data]
The advantage is that it is easy to filter your arguments:
doSomething[myType[d_]]:=d
(* usage: *)
doSomething[var]
Now I want to allow this:
var["B"] <- must return 2
But I do not know how to do that, any idea?
What I have done so far:
myType /: Key[k_][myType[d_]:=d[k]
This works for syntax like:
Key["B"][var]
but not for
var["B"]
associations
asked yesterday
Picaud VincentPicaud Vincent
1,065517
$endgroup$
add a comment |
$begingroup$
I have some "complicated" data that I want to encapsulate into a "struct":
For instance (imagine that data have several fields):
data=<|"A"->6,"B"->2|>
var=myType[data]
The advantage is that it is easy to filter your arguments:
doSomething[myType[d_]]:=d
(* usage: *)
doSomething[var]
Now I want to allow this:
var["B"] <- must return 2
But I do not know how to do that, any idea?
What I have done so far:
myType /: Key[k_][myType[d_]:=d[k]
This works for syntax like:
Key["B"][var]
but not for
var["B"]
associations
asked yesterday
Picaud VincentPicaud Vincent
1,065517
$endgroup$
I have some "complicated" data that I want to encapsulate into a "struct":
For instance (imagine that data have several fields):
data=<|"A"->6,"B"->2|>
var=myType[data]
The advantage is that it is easy to filter your arguments:
doSomething[myType[d_]]:=d
(* usage: *)
doSomething[var]
Now I want to allow this:
var["B"] <- must return 2
But I do not know how to do that, any idea?
What I have done so far:
myType /: Key[k_][myType[d_]:=d[k]
This works for syntax like:
Key["B"][var]
but not for
var["B"]
associations
associations
asked yesterday
Picaud VincentPicaud Vincent
1,065517
asked yesterday
Picaud VincentPicaud Vincent
1,065517
edited yesterday
Picaud Vincent
asked yesterday
Picaud VincentPicaud Vincent
1,065517
asked yesterday
Picaud VincentPicaud Vincent
1,065517
asked yesterday
Picaud VincentPicaud Vincent
1,065517
1,065517
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
ClearAll[myType]
myType /: myType[data_Association][s_String] := data[[s]]
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
2
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
$endgroup$
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
$begingroup$
This definitely works, though it's good to notice that this sets aSubValueformyType, not anUpValue.
$endgroup$
– Sjoerd Smit
yesterday
add a comment |
$begingroup$
You certainly can make the definition you want using TagSetDelayed, but doing so just obfuscates the fact that you aren't setting an UpValue at all, as was pointed out in the comment above.
The direct way to set this definition is just
myType[assoc_?AssociationQ][key_] := assoc[key]
Doing it like this makes it clear what you are doing. Looking at the code with TagSetDelayed you has to stare at it for a second wondering what the actual definition is, whereas this definition is clear.
On a side note, if you want a more restrictive definition, one that only applies when the key is present in the association you could use
myType[KeyValuePattern[{key_ -> val_}]][key_] := val
which returns unevaluated when the key isn't present
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
(* 2 *)
var["E"]
(* myType[<|"A" -> 6, "B" -> 2|>]["E"] *)
answered yesterday
Jason B.Jason B.
48.3k388190
$endgroup$
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking usingTagSetDelayeddoes not really mean trying to set anUpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for settingUpValuesas for every other possibility (DownValuesandSubValues) the default is all that is possible to choose and usingTagSetDelayedin those cases is redundant...
$endgroup$
– Albert Retey
13 hours ago
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
ClearAll[myType]
myType /: myType[data_Association][s_String] := data[[s]]
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
2
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
$endgroup$
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
$begingroup$
This definitely works, though it's good to notice that this sets aSubValueformyType, not anUpValue.
$endgroup$
– Sjoerd Smit
yesterday
add a comment |
$begingroup$
ClearAll[myType]
myType /: myType[data_Association][s_String] := data[[s]]
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
2
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
$endgroup$
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
$begingroup$
This definitely works, though it's good to notice that this sets aSubValueformyType, not anUpValue.
$endgroup$
– Sjoerd Smit
yesterday
add a comment |
$begingroup$
ClearAll[myType]
myType /: myType[data_Association][s_String] := data[[s]]
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
2
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
$endgroup$
ClearAll[myType]
myType /: myType[data_Association][s_String] := data[[s]]
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
2
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
answered yesterday
Henrik SchumacherHenrik Schumacher
52.1k470147
52.1k470147
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
$begingroup$
This definitely works, though it's good to notice that this sets aSubValueformyType, not anUpValue.
$endgroup$
– Sjoerd Smit
yesterday
add a comment |
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
$begingroup$
This definitely works, though it's good to notice that this sets aSubValueformyType, not anUpValue.
$endgroup$
– Sjoerd Smit
yesterday
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
Thanks again Henrik, my questions are too easy :-)
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
$begingroup$
You're welcome.
$endgroup$
– Henrik Schumacher
yesterday
2
2
$begingroup$
This definitely works, though it's good to notice that this sets a
SubValue for myType, not an UpValue.$endgroup$
– Sjoerd Smit
yesterday
$begingroup$
This definitely works, though it's good to notice that this sets a
SubValue for myType, not an UpValue.$endgroup$
– Sjoerd Smit
yesterday
add a comment |
$begingroup$
You certainly can make the definition you want using TagSetDelayed, but doing so just obfuscates the fact that you aren't setting an UpValue at all, as was pointed out in the comment above.
The direct way to set this definition is just
myType[assoc_?AssociationQ][key_] := assoc[key]
Doing it like this makes it clear what you are doing. Looking at the code with TagSetDelayed you has to stare at it for a second wondering what the actual definition is, whereas this definition is clear.
On a side note, if you want a more restrictive definition, one that only applies when the key is present in the association you could use
myType[KeyValuePattern[{key_ -> val_}]][key_] := val
which returns unevaluated when the key isn't present
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
(* 2 *)
var["E"]
(* myType[<|"A" -> 6, "B" -> 2|>]["E"] *)
answered yesterday
Jason B.Jason B.
48.3k388190
$endgroup$
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking usingTagSetDelayeddoes not really mean trying to set anUpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for settingUpValuesas for every other possibility (DownValuesandSubValues) the default is all that is possible to choose and usingTagSetDelayedin those cases is redundant...
$endgroup$
– Albert Retey
13 hours ago
add a comment |
$begingroup$
You certainly can make the definition you want using TagSetDelayed, but doing so just obfuscates the fact that you aren't setting an UpValue at all, as was pointed out in the comment above.
The direct way to set this definition is just
myType[assoc_?AssociationQ][key_] := assoc[key]
Doing it like this makes it clear what you are doing. Looking at the code with TagSetDelayed you has to stare at it for a second wondering what the actual definition is, whereas this definition is clear.
On a side note, if you want a more restrictive definition, one that only applies when the key is present in the association you could use
myType[KeyValuePattern[{key_ -> val_}]][key_] := val
which returns unevaluated when the key isn't present
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
(* 2 *)
var["E"]
(* myType[<|"A" -> 6, "B" -> 2|>]["E"] *)
answered yesterday
Jason B.Jason B.
48.3k388190
$endgroup$
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking usingTagSetDelayeddoes not really mean trying to set anUpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for settingUpValuesas for every other possibility (DownValuesandSubValues) the default is all that is possible to choose and usingTagSetDelayedin those cases is redundant...
$endgroup$
– Albert Retey
13 hours ago
add a comment |
$begingroup$
You certainly can make the definition you want using TagSetDelayed, but doing so just obfuscates the fact that you aren't setting an UpValue at all, as was pointed out in the comment above.
The direct way to set this definition is just
myType[assoc_?AssociationQ][key_] := assoc[key]
Doing it like this makes it clear what you are doing. Looking at the code with TagSetDelayed you has to stare at it for a second wondering what the actual definition is, whereas this definition is clear.
On a side note, if you want a more restrictive definition, one that only applies when the key is present in the association you could use
myType[KeyValuePattern[{key_ -> val_}]][key_] := val
which returns unevaluated when the key isn't present
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
(* 2 *)
var["E"]
(* myType[<|"A" -> 6, "B" -> 2|>]["E"] *)
answered yesterday
Jason B.Jason B.
48.3k388190
$endgroup$
You certainly can make the definition you want using TagSetDelayed, but doing so just obfuscates the fact that you aren't setting an UpValue at all, as was pointed out in the comment above.
The direct way to set this definition is just
myType[assoc_?AssociationQ][key_] := assoc[key]
Doing it like this makes it clear what you are doing. Looking at the code with TagSetDelayed you has to stare at it for a second wondering what the actual definition is, whereas this definition is clear.
On a side note, if you want a more restrictive definition, one that only applies when the key is present in the association you could use
myType[KeyValuePattern[{key_ -> val_}]][key_] := val
which returns unevaluated when the key isn't present
var = myType[<|"A" -> 6, "B" -> 2|>];
var["B"]
(* 2 *)
var["E"]
(* myType[<|"A" -> 6, "B" -> 2|>]["E"] *)
answered yesterday
Jason B.Jason B.
48.3k388190
answered yesterday
Jason B.Jason B.
48.3k388190
answered yesterday
Jason B.Jason B.
48.3k388190
answered yesterday
Jason B.Jason B.
48.3k388190
48.3k388190
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking usingTagSetDelayeddoes not really mean trying to set anUpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for settingUpValuesas for every other possibility (DownValuesandSubValues) the default is all that is possible to choose and usingTagSetDelayedin those cases is redundant...
$endgroup$
– Albert Retey
13 hours ago
add a comment |
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking usingTagSetDelayeddoes not really mean trying to set anUpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for settingUpValuesas for every other possibility (DownValuesandSubValues) the default is all that is possible to choose and usingTagSetDelayedin those cases is redundant...
$endgroup$
– Albert Retey
13 hours ago
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
thanks for the clarifications
$endgroup$
– Picaud Vincent
yesterday
$begingroup$
to be nit-picking using
TagSetDelayed does not really mean trying to set an UpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for setting UpValues as for every other possibility (DownValues and SubValues) the default is all that is possible to choose and using TagSetDelayed in those cases is redundant...$endgroup$
– Albert Retey
13 hours ago
$begingroup$
to be nit-picking using
TagSetDelayed does not really mean trying to set an UpValue, it just more explicitly states to which symbol the rule should be associated. Of course in practice the only relevant case where you would use it is for setting UpValues as for every other possibility (DownValues and SubValues) the default is all that is possible to choose and using TagSetDelayed in those cases is redundant...$endgroup$
– Albert Retey
13 hours ago
add a comment |
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