Simon O'Rorke

I'm also reporting this bug direct to Cycling '74 Support. But it is here in the forum for the information of the community.

 object where only one item has been set, the Dict's 

 is the number of characters in the key of the single item that was set, with each successive key consisting of the corresponding character of the key that was set. So, for example, if the one key set was "ABC", 

 method for each of these single-character keys returns a null value.

The count of keys is the length of the single key that was set. In the above example, that would be 3.

Example Patcher and Javascript Files That Together Show the Bug

DictBug.zip

 object. This is demonstrated by the interactions involving the Max 

 object that is included in the attached patcher for comparison.

If a second item is added to the Javascript 

 object, the first item can then be retrieved correctly. This is demonstrated in the attached patcher/Javascript example.

If it is possible that data may be retrieved from a 

 when only one item has been set, the corruption can be fixed by initialising the 

var testDict = new Dict("testDict");
testDict.set("Dummy1", "Needed for Dict bug workaround");
testDict.set("Dummy2", "Needed for Dict bug workaround");

The dummy items can then be studiously ignored in subsequent processing or even removed once two real items have been added.

Max Version: 8.2.0 (The bug also occurs in 8.1.11.)

In a Javascript Dict object where only one item has been set, the Dict's getkeys() method returns n keys, where n is the number of characters in the key of the single item that was set, with each successive key consisting of the corresponding character of the key that was set. So, for example, if the one key set was "ABC", getkeys() will return "A", "B" and "C". The get() method for each of these single-character keys returns a null value.

1) In a Max js Javascript file, create an empty Dict object. For example:

2) Add a single item to the Dict. For example:

3) Count the keys in the Dict. For example:

The bug is specific to the Javascript Dict object. It does not occur with the Max dict object. This is demonstrated by the interactions involving the Max dict object that is included in the attached patcher for comparison.

If a second item is added to the Javascript Dict object, the first item can then be retrieved correctly. This is demonstrated in the attached patcher/Javascript example.

If it is possible that data may be retrieved from a Dict when only one item has been set, the corruption can be fixed by initialising the Dict with two dummy items. For example:

Bug Report
I'm also reporting this bug direct to Cycling '74 Support. But it is here in the forum for the information of the community.
Max 

bug-report-in-a-javascript-dict-where-only-one-item-has-been-set-the-data-is-corrupt-when-retrieved

Thanks. Do you happen to know if the Dict object is supported in built applications now?

Sorry, I don’t know. I’ve got no experience with built applications.

Well Ill get to checking it eventually. No worries )

It’s a super confusing design or bug, but it’s always been this way. It’s returning a string of the one key rather than an array of strings, so calling .length is returning the number of characters in the string. You need to type check what gets returned from getkeys(). If it’s a string rather than an array then the length is one.

It’s a super confusing design or bug, but it’s always been this way. It’s returning a string of the one key rather than an array of strings, so  calling .length is returning the number of characters in the string.   You need to type check what gets returned from getkeys().  If it’s a string rather than an array then the length is one.

Thanks for the insights, Tyler! I've updated the example Javascript file to add the type of the keys variable returned by 

 to the diagnostic information that is output to the Max console:

js: DictBug: Creating Dict 
js: DictBug: Setting value of key '0ABC' to 'a00'  
js: DictBug: Dict.getkeys() returned 4 keys: 
js:     key = '0'; value = 'null' 
js:     key = 'A'; value = 'null' 
js:     key = 'B'; value = 'null' 
js:     key = 'C'; value = 'null' 
js:     (The type of the keys variable returned by getkeys is string) 
js: DictBug: Setting value of key '1BCD' to 'b10,b11'  
js: DictBug: Dict.getkeys() returned 2 keys: 
js:     key = '0ABC'; value = 'a00' 
js:     key = '1BCD'; value = 'b10,b11' 
js:     (The type of the keys variable returned by getkeys is object)

As you say, the keys variable's type is string when there's only one item, though it is object when there's more than one.

As the above diagnostic log also shows, the one item's value cannot be retrieved. If this was a design feature rather than a bug, some compensating advantage might be expected. But I cannot see what that might be. Furthermore, the behaviour of the Javascript 

 object and is counter to the documentation. So, notwithstanding the age of the behaviour, a good case can be made that it is a bug rather than a feature.

One reason why the Max developers might be reluctant to fix a long-standing bug would be if the workarounds that user developers have coded were to break their code if Cycling '74 were to fix the bug. I'm confident that the workaround I have implemented, on the lines of what I wrote in my previous post, will not break my code if the Max Javascript bug is fixed.

Thanks for the insights, Tyler!  I've updated the example Javascript file to add the type of the keys variable returned by getkeys() to the diagnostic information that is output to the Max console:

As the above diagnostic log also shows, the one item's value cannot be retrieved.  If this was a design feature rather than a bug, some compensating advantage might be expected.  But I cannot see what that might be.  Furthermore, the behaviour of the Javascript Dict object differs from that of the Max dict object and is counter to the documentation. So, notwithstanding the age of the behaviour, a good case can be made that it is a bug rather than a feature.

One reason why the Max developers might be reluctant to fix a long-standing bug would be if the workarounds that user developers have coded were to break their code if Cycling '74 were to fix the bug.   I'm confident that the workaround I have implemented, on the lines of what I wrote in my previous post, will not break my code if the Max Javascript bug is fixed.

Cycling '74 Support have confirmed that this is a known bug.

Bug Report: In a Javascript Dict where only one item has been set, the data is corrupt when retrieved.