In Java you *cannot* annotate any language element. You can annotate
class, methods, instance variables, method arguments and temporaries
and packages.
Then when I take an annotation, for example an hibernate annotation:
@Entity
@Table(name = "EMPLOYEE")
In the case of Hibernate, these annotation are for a class and they
are used at *runtime* to bind the class instances with database
entries (elements of this class are stored in the table EMPLOYEE).
Now I've never seen anyone doing that, but as you can access the
annotation at runtime, and you can extract from the annotation its
name and its parameters (for example you could extract "Table" and
"name -> EMPLOYEE". Then, using the Java reflective features, you can
do something like:
method = obj.getClass().getMethod(methodName, param1.class,
param2.class, ..);
method.invoke(obj, arg1, arg2,...);
And this way you execute a method named "Table", "name" or "EMPLOYEE"
with the parameter you want, as you could execute a method from any
string matching a method name. We have the same primitive in Pharo on
CompiledMethod.
I would not say that pragmas are more powerful in Java. Can you give
an example of something you can do with the Java annotation that you
can't do with Pharo pragmas ?
Out of a curiosity, how can I annotate class, instance variable,
method argument or temporary, or package.
How can I annotate the pragma definition itself? How can I retrieve
annotations of a pragma definition?
I mean, I understand that you can *achieve* same effect, but you *can*
achieve it as well with no pragma support at all.
Jan
In Slang we use pragma to annotate argument and temporary variables
and it works just fine. When you describe in Pharo classes and
instance variables using Magritte you can do the same thing as just
annotating them.
Stef
