This is code extracted from this project (note: reformatted for clarity):
Class Util.Data.EmojiType Extends %Persistent
{
Property CodePoint As %Integer;
Property UnicodeChar As %String [
Calculated,
ReadOnly,
SqlComputeCode = { set {*} = $wchar({CodePoint})},
SqlComputed,
Transient
];
// snip
Method UnicodeCharGet() As %String
{
quit $wchar(..CodePoint)
}
Now, I really don't get it. Why is it that UnicodeChar is both Calculated and has a custom getter (ouch), plus the custom getter does exactly the same thing as the SqlComputeCode?
And if I try and get this property, what part of all this will be triggered?
Custom getter can be called even if property is not Calculated. But works only in object access mode. And to get calculated value via SQL query, property should have defined all properties: Calculated, SqlComputed and SqlComputeCode. And in case where SqlComputeCode is defined, this code uses only in SQL query. When property has Calculated property, but not SqlComputed, it will not appear in SQL result.
SqlComputed, Calculated
Related
The reference documentation for the class NSUniqueIdentifier claims that unique ID specifiers are evaluated in the following scheme:
If the container implements a method whose selector matches the relevant valueIn<Key>WithUniqueID: pattern established by scripting
key-value coding, the method is invoked. This method can potentially
be very fast, and it may be relatively easy to implement.
As is the case when evaluating any script object specifier, the container of the specified object is given a chance to evaluate the
object specifier. If the container class implements the
indicesOfObjectsByEvaluatingObjectSpecifier: method, the method is
invoked. This method can potentially be very fast, but it is
relatively difficult to implement.
An NSWhoseSpecifier object that specifies the first object whose relevant 'ID ' attribute matches the ID is synthesized and evaluated.
The NSWhoseSpecifier object must search through all of the keyed
elements in the container, looking for a match. The search is
potentially very slow.
However, I am not seeing valueIn<Key>WithUniqueID: getting called. To give you an example, I have a class where I describe the object specifier in the following way:
- (NSScriptObjectSpecifier *)objectSpecifier
{
assert(self.documentID);
assert(self.controller);
NSScriptObjectSpecifier *containerRef = self.controller.objectSpecifier;
assert(containerRef);
assert(containerRef.keyClassDescription);
return [[NSUniqueIDSpecifier alloc] initWithContainerClassDescription:containerRef.keyClassDescription
containerSpecifier:containerRef
key:#"allObjects"
uniqueID:self.documentID];
}
The method I have defined in the container class is - (id)valueInAllObjectsWithUniqueID:(NSString *)uniqueID is the method I have defined:
- (id)valueInAllObjectsWithUniqueID:(NSString *)uniqueID {
return [self objectWithIdentifier:uniqueID];
}
In the class corresponding to the container I've also overridden -respondsToSelector: to debug this further, and observe that the only relevant method the scripting system queries is indicesOfObjectsByEvaluatingObjectSpecifier: right after -objectSpecifier above is called (and confirmed to return a non-nil result with the container class description and container specifier consistent with the container's class receiving method calls right after the object specifier is evaluated).
Any ideas? This is on OSX Mavericks (10.9.4).
I'm creating XML documents with VBScript and MSXML DOM. In order to structure and simplify my code I'm using classes and thus methods (functions in VBS) too.
Here is a little function that troubles me:
function createAttribute(name, value)
dim doc
Set doc = CreateObject("Msxml2.DOMDocument.4.0")
dim attr
set attr= doc.createNode(2,name,"")
attr.NodeValue=value
createAttribute=attr
end function
The assignment createAttribute=attr, where I'm setting the return value of the function, causes the following error:
Object doesn't support this property or method
As the web resources on XML processing with VBS are rather sparse, I hope some of you can help me to understand whats going on here. Here are my questions:
What object does not support what property or method?
Can i pass objects of any given class as return values of VBS functions?
Can i pass an object of the class IXMLDOMAttribute as a return value to a VBS function?
I think the problem is that attr is an object, so you need to use set to apply the return value. Otherwise, you may simply be returning attr's default property value (if it has one):
set createAttribute = attr
You don't show how you use the return value, so I can't comment on that but it is possibly the source of the error.
Grails has a bug with regards to databinding in that it throws a cast exception when you're dealing with bad numerical input. JIRA: http://jira.grails.org/browse/GRAILS-6766
To fix this I've written the following code to manually handle the numerical input on the POGO class Foo located in src/groovy
void setPrice(String priceStr)
{
this.priceString = priceStr
// Remove $ and ,
priceStr = priceStr.trim().replaceAll(java.util.regex.Matcher.quoteReplacement('$'),'').replaceAll(',','')
if (!priceStr.isDouble()) {
errors.reject(
'trade.price.invalidformat',
[priceString] as Object[],
'Price:[{0}] is an invalid price.')
errors.rejectValue(
'price',
'trade.price.invalidformat')
} else {
this.price = priceStr.toDouble();
}
}
The following throws a null reference exception on the errors.reject() line.
foo.price = "asdf" // throws null reference on errors.reject()
foo.validate()
However, I can say:
foo.validate()
foo.price = "asdf" // no Null exception
foo.hasErrors() // false
foo.validate()
foo.hasErrors() // true
Where does errors come from when validate() is called?
Is there a way to add the errors property without calling validate() first?
I can't exactly tell you why, but you need to call getErrors() explicitly instead of accessing it as errors like a property. For some reason, Groovy isn't calling the method for it. So change the reject lines in setPrice() to
getErrors().reject(
'trade.price.invalidformat',
[priceString] as Object[],
'Price:[{0}] is an invalid price.')
getErrors().rejectValue(
'price',
'trade.price.invalidformat')
That is the easiest way to make sure the Errors object exists in your method. You can check out the code that adds the validation related methods to your domain class.
The AST transformation handling #Validateable augments the class with, among other things
a field named errors
public methods getErrors, setErrors, clearErrors and hasErrors
The getErrors method lazily sets the errors field if it hasn't yet been set. So it looks like what's happening is that accesses to errors within the same class are treated as field accesses rather than Java Bean property accesses, and bypassing the lazy initialization.
So the fix appears to be to use getErrors() instead of just errors.
The errors are add to your validateable classes (domain classes and classes that have the annotation #Validateable) dinamically.
Allowing the developer to set a String instead of a number doesn't seem a good way to go. Also, your validation will work only for that particular class.
I think that a better approach is to register a custom property editor for numbers. Here's a example with dates, that enable the transform of String (comming from the form) to Date with a format like dd/MM/yyyy. The idea is the same, as you will enforce that your number is parseable (eg. Integer.parseInt() will throw exception).
In your domain class, use the numeric type instead of String, so by code developers will not be allowed to store not number values.
I'm trying to see if there's a way to get a refference of an object which is outside the local (and global) scope, but who exists in memory.
Let's say in my program, i've instantiated an object whose reference is this:
{O:9*\PROGRAM=ZAVG_DELETE_THIS\CLASS=LCL_SMTH}
Far away after tons of calls, in a context where i wouldn't be able to access this object, could i do something like getting the reference of this object simply by knowing the above string?
I was looking into the cl_abap_*descr classes, but i haven't found a method that takes the 'program_name', 'class_name' and 'instance_number', to return the reference of an object.
I'm trying to do this for the purpose of debugging, not to build something that works.
[EDIT 1]:
I assumed that the o:9 string was required in order to get the reference of the object. As pointed out in the response of #mydoghasworms, this isn't the case. It seems that i only need the local name of the variable which holds the reference.
I hope I understand your question correctly, because I am not sure what you mean with "for the purpose of debugging", but here goes:
You can access the variables of another program that are loaded in the memory of the same session (I am pretty sure it does not need to be in the call stack) using:
ASSIGN ('(PROGRAM)VARIABLE') TO LV_LOCAL.
With reference variables, it becomes a bit more tricky, but here is an example that will help to demonstrate.
Here is our calling program that contains a reference variable LR_TEST which we want to access somewhere else. For the purpose of the demonstration, I make reference to a locally defined class (because that's what I gather from your question).
REPORT ZCALLER.
class lcl_test definition.
public section.
data: myval type i.
methods: my_meth exporting e_val type i.
endclass.
data: lr_test type ref to lcl_test.
CREATE OBJECT lr_test.
lr_test->MYVAL = 22.
perform call_me(zcallee).
class lcl_test implementation.
method my_meth.
* Export the attribute myval as param e_val.
e_val = myval.
endmethod.
endclass.
Here is the program in which we want to access a variable from the above program.
REPORT ZCALLEE.
form call_me.
field-symbols: <ref>.
data: ld_test type ref to object.
data: lv_val type i.
* Exhibit A: Gettinf a reference to a 'foreign' object instance
assign ('(ZCALLER)LR_TEST') to <ref>.
* <ref> now contains a reference to the class instance from the program
* ZCALLER (not very useful, except for passing around maybe)
* Exhibit B: Getting a public attribute from a 'foreign' class instance
assign ('(ZCALLER)LR_TEST->MYVAL') to <ref>.
* <ref> now contains the value of the attribute MYVAL
* Exhibit C: Getting a reference to an instance and calling a method
assign ('(ZCALLER)LR_TEST') to <ref>. "Again the class reference
if sy-subrc = 0. "Rule: Always check sy-subrc after assign before
"accessing a field symbol! (but you know that)
ld_test = <ref>. "Now we have a concrete handle
* Now we make a dynamic method call using our instance handle
CALL METHOD ld_test->('MY_METH')
IMPORTING
e_val = lv_val.
endif.
endform.
I was following a tutorial today that had me scratching my head for an hour. Consider:
public class MyClass {
public int getTotal() {
amount = 100;
return amount;
}
}
and an excerpt from a JSP:
<p>Total: ${objectOfTypeMyClass.total}</p> //object instantiated elsewhere
Nowhere in the code was an instance variable named "total" ever declared or used. The only reference to the word "total" in the whole project (other than in the JSP) was the method getTotal().
So after some desperate last-ditch experimentation, it appears that Expression Language evaluates ${someObject.var} as "call the getVar() method of the someObject object.
I worked with this long tutorial for over a week thinking that ${someObject.var} was saying "directly fetch the saved instance variable "var" from someObject.
Did I have it wrong the whole time and is my observation correct that in order to reference any instance variable using EL, you have to provide a corresponding getter method named getVarname() where "Varname" is the name of the instance variable?
Also, EL seems to be case-insensitive in this regard. In my example above, "total" in ${objectOfTypeMyClass.total} is all lowercase where the method getTotal() has a capital "T".
And while we're at it, why don't we need to instantiate the variable "total"? I guess EL isn't actually referencing an instance variable...just a getter method?
What gives?
Did I have it wrong the whole time and is my observation correct that in order to reference any instance variable using EL, you have to provide a corresponding getter method named getVarname() where "Varname" is the name of the instance variable?
That's correct. EL adheres the JavaBeans specification as described in the EL specification.
Also, EL seems to be case-insensitive in this regard. In my example above, "total" in ${objectOfTypeMyClass.total} is all lowercase where the method getTotal() has a capital "T".
No, it's certainly not case insensitive. It's specified behaviour. ${bean.Total} would not have worked.
And while we're at it, why don't we need to instantiate the variable "total"? I guess EL isn't actually referencing an instance variable...just a getter method?
It's because it's supposed to adhere the Javabean specification.
All with all, read the both specifications and everything will be clear :)
See also:
What are the advantages of Javabeans?
The . in objectOfTypeMyClass.total is the JSTL EL Dot Operator. It can do a few different things. Including:
map.key accessed a value from map stored under key. or
object.property accesses property from object using "JavaBeans" conventions.
This should work:
public class MyClass {
private int total = 100;
public int getTotal() {
return total;
}
...
}