I have such argument which is needed in my eclipse product:
http://some_url/api/v1/
when I debug the app I can use Program Arguments with own argument:
${my_api}
but it is local argument. When I tried to get arguments from the platform I saw that I only can get strings array:
Platform.getApplicationArgs()
so each argument has to be at the certain place because programmatically for example I get element on the 1 (0) position. Maybe I can add some keys to identify each program argument and get it like dictionary item for example?
Related
I've found the InvokeDynamic class and have made it work with a static method handle acquired via MethodHandles.Lookup.findStatic().
Now I am trying to do the same thing, but with a virtual method handle acquired via MethodHandles.Lookup.findVirtual().
I can cause my bootstrap method to run, and I make sure in my bootstrap method that I'm returning a ConstantCallSite(mh), where mh is the result of calling MethodHandles.Lookup.findVirtual(). (This part all works fine, i.e. I understand how "indy" works.)
However, when I use the resulting Implementation as the argument to an intercept() call, I cannot pass the actual object on which the method represented by the method handle is to be invoked. This is due to the withArgument() method being used for two contradictory purposes.
Here is my recipe:
Implementation impl =
InvokeDynamic.bootstrap(myBootstrapDescription, someOtherConstantArgumentsHere)
.invoke(theMethodName, theMethodReturnType)
// 0 is the object on which I want to invoke my virtual-method-represented-by-a-method-handle;
// 1 is the sole argument that the method actually takes.
.withArgument(0, 1);
There are some problems here.
Specifically, it seems that withArgument() is used by ByteBuddy for two things, not just one:
Specifying the parameter types that will be used to build a MethodType that will be supplied to the bootstrap method. Let's say my virtual method takes one argument.
Specifying how the instrumented method's arguments are passed to the actual method handle execution.
If I have supplied only one argument, the receiver type is left unbound and execution of the resulting MethodHandle cannot happen, because I haven't passed an argument that will be used for the receiver type "slot". If I accordingly supply two arguments to (1) above (as I do in my recipe), then the method handle is not found by my bootstrap method, because the supplied MethodType indicates that the method I am searching for requires two arguments, and my actual method that I'm finding only takes one.
Finally, I can work around this (and validate my hypothesis) by doing some fairly ugly stuff in my bootstrap method:
First, I deliberately continue to pass two arguments, not one, even though my method only takes two arguments: withArgument(0, 1)
In my bootstrap method, I now know that the MethodType it will receive will be "incorrect" (it will have two parameter types, not one, where the first parameter type will represent the receiver type). I drop the first parameter using MethodType#dropParameterTypes(int, int).
I call findVirtual() with the new MethodType. It returns a MethodType with two parameter types: the receiver type that it adds automatically, and the existing non-dropped parameter type.
(More simply I can just pass a MethodType as a constant to my bootstrap method via, for example, JavaConstant.MethodType.of(myMethodDescription) or built however I like, and ignore the one that ByteBuddy synthesizes. It would still be nice if there were instead a way to control the MethodType that ByteBuddy supplies (is obligated to supply) to the bootstrap method.)
When I do things like this in my bootstrap method, my recipe works. I'd prefer not to tailor my bootstrap method to ByteBudddy, but will here if I have to.
Is it a bug that ByteBuddy does not seem to allow InvokeDynamic to specify the ingredients for a MethodType directly, without also specifying the receiver?
What you described, is entirely independent of Byte-Buddy. It’s just the way how invokedynamic works.
JVMS, §5.4.3.6
5.4.3.6. Dynamically-Computed Constant and Call Site Resolution
To resolve an unresolved symbolic reference R to a dynamically-computed constant or call site, there are three tasks. First, R is examined to determine which code will serve as its bootstrap method, and which arguments will be passed to that code. Second, the arguments are packaged into an array and the bootstrap method is invoked. Third, the result of the bootstrap method is validated, and used as the result of resolution.
…
The second task, to invoke the bootstrap method handle, involves the following steps:
An array is allocated with component type Object and length n+3, where n is the number of static arguments given by R (n ≥ 0).
The zeroth component of the array is set to a reference to an instance of java.lang.invoke.MethodHandles.Lookup for the class in which R occurs, produced as if by invocation of the lookup method of java.lang.invoke.MethodHandles.
The first component of the array is set to a reference to an instance of String that denotes N, the unqualified name given by R.
The second component of the array is set to the reference to an instance of Class or java.lang.invoke.MethodType that was obtained earlier for the field descriptor or method descriptor given by R.
Subsequent components of the array are set to the references that were obtained earlier from resolving R's static arguments, if any. The references appear in the array in the same order as the corresponding static arguments are given by R.
A Java Virtual Machine implementation may be able to skip allocation of the array and, without any change in observable behavior, pass the arguments directly to the bootstrap method.
So the first three arguments to the bootstrap method are provided by the JVM according to the rules cited above. Only the other arguments are under the full control of the programmer.
The method type provided as 3rd argument always matches the type of the invokedynamic instruction describing the element types to pop from the stack and the type to push afterwards, if not void. Since this happens automatically, there’s not even a possibility to create contradicting, invalid bytecode in that regard; there is just a single method type stored in the class file.
If you want to bind the invokedynamic instruction to an invokevirtual operation using a receiver from the operand stack, you have exactly the choices already mentioned in your question. You may derive the method from other bootstrap arguments or drop the first parameter type of the instruction’s type. You can also use that first parameter type to determine the target of the method lookup. There’s nothing ugly in this approach; it’s the purpose of bootstrap methods to perform adaptations.
I am trying to assign the value of this stucture path to a fieldsymbol, but this path does not work because it has a table in it's path.
But with in the debugger this value of this path is shown correctly.
Is there a way to dynamically assign a component of a table line to a fieldsymbol, by passing one path?
If not then I will just read the table line and then use the path to get the wanted value.
ls_struct (Struct)
- SUPPLYCHAINTRADETRANSACTION (Struct)
- INCL_SUPP_CHAIN_ITEM (Table)
- ASSOCIATEDDOCUMENTLINEDOCUMENT (Element)
i_component_path = |IG_DDIC-SUPPLYCHAINTRADETRANSACTION-INCL_SUPP_CHAIN_ITEM[1]-ASSOCIATEDDOCUMENTLINEDOCUMENT|.
ASSIGN (i_component_path) TO FIELD-SYMBOL(<lg_value>).
IF <lg_value> IS NOT ASSIGNED.
return.
ENDIF.
<lg_value> won't be assigned
Solution by Sandra Rossi
The debugger has its own syntax and own logic, it doesn't apply the ASSIGN algorithm at all. With ABAP source code, you have to use ASSIGN twice, the first one to reach the internal table, then you select the first line, and the second one to reach the component of the line.
The debugger works completely differently, the debugger code works only in debug mode, you can't call the code from the debugger (i.e. if you call it, the kernel code used by the debugger will fail). No, there's no "abappath". There are the XSL transformation objects (xpath), but it's slow for what you ask.
Thank you very much
This seems to be a rather unexpected limitation of the ASSIGN statement. Probably worth a ticket to SAP's ABAP language group to clarify whether it's even a bug.
While this works:
ASSIGN data-some_table[ 1 ]-some_field TO FIELD-SYMBOL(<lv_source>).
the same expressed as a string doesn't:
ASSIGN (`data-some_table[ 1 ]-some_field`) TO FIELD-SYMBOL(<lv_source>).
Alternative 1 for (name) of the ABAP keyword documentation for the ASSIGN statement says that "[t]he name in name is structured in the same way as if specified directly".
However, this declaration is immediately followed by "the content of name must be the name of a data object which may contain offsets and lengths, structure component selectors, and component selectors for assigning structured data objects and attributes in classes or objects", a list that does not include the table expressions we would need here.
I have a pointer to an array or to a variable. I want to get the name of that array or variable. How to get this in LLVM?
I am trying to instrument a function to which an array or variable is passed through pointer. I want to get the name of that array or variable argument. I am instrumenting my functions using LLVM.
You need to use debug information for that, because otherwise names from the original C code do not get represented in LLVM IR, in the general case. See the debug info document. In particular, look in the sections about "#llvm.dbg.declare" and "Global Value Descriptors"
I have a simple tfs-2010 build definition using the default process template. In it I defined the Build Number Format using $(BuildID) to define part of the computed field. This works and I can see what BuildID's value is.
Now I try to pass the BuildID property to MSBuild as an argument:
/p:SomeProperty=$(BuildID)
However when I look at the build log I see SomeProperty literally equals $(BuildID) rather then the value of BuildID.
What am I missing?
Update for clarity: What I'm asking is how to reference as a Build Process Parameter in the Build Definition. For example Build Number Format has a default expression of $(BuildDefinitionName)_$(Date:yyyyMMdd)$(Rev:.r)
You need to use a VB.NET expression. For example:
String.Format("/p:SomeProperty={0}", BuildDetail.BuildNumber)
The Build Number tokens, e.g. $(BuildDefinitionName), are specific to the Build Number Format process parameter. They aren't tokens that you can use anywhere else in the build process. Most are available in the BuildDetail object or from the environment. The Build Id is a bit of a special case, however. It comes from the identity column of the builds table and isn't directly exposed in our public API. You could extract it from the BuildNumber, like this:
BuildDetail.BuildNumber.Substring(BuildDetail.BuildNumber.LastIndexOf('/') + 1)
Note that you would need to do this in the XAML directly rather than putting a VB expression into the build process parameter editor GUI. That's because those values just get passed through as literal strings.
Is there anyway to specify more than one MergeSection value for the MSBuild LINK task? (The MergeSection param is the same as the /merge param for link.exe)
http://msdn.microsoft.com/en-us/library/ee862471.aspx
When calling link.exe you can specify more than one /merge value, but that doesn't seem possible with the MergeSection parameter.
So far the only way I can see to make this work is by using the AddtionalOptions param, but I'm hoping there's a better way to implement this parameter.
Thanks
I think you may have to use AdditionalOptions.
In the Link task the MergeSections property is a string value, not an array, so you can only set one string. Link.exe does not seem to allow you to pass multiple pairs in one command line parameter, you must specify a separate MERGE command line parameter for each pair. The Visual Studio property page only allows a single string for the MergeSections property.