Hi Mandy,
On 09/21/2017 05:15 PM, mandy chung wrote:
Hi Peter,
Updated webrev:
http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.03/
On 9/3/17 7:02 AM, Peter Levart wrote:
Updated webrev:
http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.02/
That's what I had in mind, yes.
Looking at the method names, I have a second thought about the too
general StackFrame::getDescriptor(). Not looking at the javadocs, one
could ask: "what is a descriptor of a stack frame?". I don't know,
maybe getMethodDescriptor() would be more to the point or even
getMethodTypeDescriptor() (since it is a descriptor of method
parameter and return types, not containing method name). What do you
and others think?
Descriptor is specified in JVMS 4.3:
A /descriptor/ is a string representing the type of a field or method.
I initially had getMethodDescriptor() while "Method" is kinda
redundant since StackFrame represents a method invocation. Descriptor
in this context is for a method and never be a field. Hence I like
Remi's suggestion to rename it to getDescriptor.
Ok, I buy it.
Although it is not expected for StackFrame interface to be
implemented by custom classes, it is a public interface. I have seen
3rd party code implementing JDK interface that was not meant to be
implemented by custom classes just because the interface seemed
appropriate. To keep binary compatibility with such potential
implementations, those two new methods could be default methods
throwing UOE.
Having a second thought, while it's rarely to have custom StackFrame
implementation, I agree making the new methods to be default method
that would help migration for tests or other use.
nit: while you are at it, you could remove the redundant "static"
modifier from the StackWalker.StackFrame interface declaration.
Done
Just two more things...
1st:
I was I little confused reading this part of javadoc of getDescriptor():
152 * Returns the <i>descriptor</i> of the method type for
153 * this stack frame. A method descriptor is a string
representing the
154 * types of parameters that the method takes, and a return
descriptor,
155 * representing the type of the value (if any) that the
method returns
156 * as defined by <cite>The Java™ Virtual Machine
Specification</cite>.
Wouldn't it be better to say:
152 * Returns the <i>descriptor</i> of the method type for
153 * this stack frame. A method descriptor is a string
representing the
154 * types of parameters that the method takes, and the
method's return type,
156 * as defined by <cite>The Java™ Virtual Machine
Specification</cite>.
I think there is a slight difference between "method return type" and
"the type of value (if any) that the method returns". The former is a
property of the method, the later is a property of the returned value
(primitive or reference or none) in a particular invocation of the
method and may be different (a subtype).
2nd:
I don't know in what circumstance may the MemberName.getMethodType() or
.getMethodDescriptor() return null, but the MemberName code is written
as follows:
169 if (type == null) {
170 expandFromVM();
171 if (type == null) {
172 return null;
173 }
174 }
Is there a real circumstance when this may happen? Should
StackWalker.StackFrame.getMethodType() / .getDescriptor() document that
situation or maybe transform it into an exception or error?
Regards, Peter
