In the Haxe programming language, is there anything equivalent to Java's scanner class (which reads input from the command line?) I'd like to find some way of reading text input from the command line.
Sys.stdin().readLine() is what you're looking for.
Here's an example from http://haxe.org/doc/start/neko#reading-user-input:
class Main {
static function main() {
Sys.println("What's your name?");
var input = Sys.stdin().readLine();
Sys.println(Std.format("Hello ${input}"));
Sys.exit(0);
}
}
Related
What is the use of the static initialization block in Groovy. Why does Geb use it? If the use of it is the same as in Java, then how can you initialize non-declared fields in a situtation like this?
class ManualsMenuModule extends Module {
static content = {
toggle { $("div.menu a.manuals") }
linksContainer { $("#manuals-menu") }
links { linksContainer.find("a") }
}
void open() {
toggle.click()
waitFor { !linksContainer.hasClass("animating") }
}
}
Some answers to your questions are provided in the section about the content DSL of the Geb manual.
The DSL is implemented using Groovy's methodMissing() mechanism and modification of the delegate of the closure assigned to the static content field. If you are interested in digging deeper then you can always look at the implementation in PageContentTemplateBuilder.
I'm not expert on Geb, I can only explain the groovy meaning of the code.
1st off, it's not the static initialization block like in java. In those lines static content = {...} you are assigning to a static variable a Closure instance which is evaluated and executed LATER (hence, lazy).
The closure represents a (part of) a Geb's Groovy Builder which is called by Geb framework to register/perform some tasks.
There's no Java counterpart to achieve the same, and that's the reason why groovy-based frameworks are so nice to use for testing purposes and they follow the general rule of thumb:
test code should be more abstract then the code under test
UPDATE:
This line:
toggle { $("div.menu a.manuals") }
can be rewritten like
toggle( { $("div.menu a.manuals") } )
or
def a = { $("div.menu a.manuals") }
toggle a
so it's a method invocation and not an assignment. In groovy you can omit the brackets in some cases.
I'm a new to Groovy. I used to use 'try-with-resources' construction in my Java code during work with I/O streams.
Could you please advise, is there any analogue of such construction in Groovy?
Groovy 2.3 also has withCloseable which will work on anything that implements Closeable
Groovy 3 newsflash
And Groovy 3+ supports try..with..resources as Java does
https://groovy-lang.org/releasenotes/groovy-3.0.html#_arm_try_with_resources
Have a look at the docs on Groovy IO and the associated javadoc.
It presents the withStream, withWriter, withReader constructions which are means of getting streams with auto-closeability
Simplest try-with-resources for all Groovy versions is the following (even works with AutoCloseable interface). Where class Thing is a closeable class or implements AutoCloseable.
new Thing().with { res ->
try {
// do stuff with res here
} finally {
res.close()
}
}
Which is the equivalent in later versions of Groovy doing:
new Thing().withCloseable { res ->
// do stuff with res here
}
I was working on COM/ATL. I need to use a class object as return value so that it can be used in managed code. I am able to define structure in idl file and also able to use it as return parameter when creating methods.
Below is the partial idl file implementation:
import "oaidl.idl";
import "ocidl.idl";
//Structure for message mapping of activation and deactivation
//Structures are working properly
[uuid(E2240D8B-EB97-4ACD-AC96-21F2EAFFE100)]
struct tagActivationManaged
{
WORD wMsgId;
WORD wStatus;
WORD wClient;
WORD wClientId;
};
//same manner if creating class it throws error.
[uuid(2ED2E59C-9362-46b2-80D8-471AD69BA5D5)]
class AuthenticationMessage
{
public:
Word message;
}
do I need to change any settings in MIDL.
NB: I am new to COM programming.
You just can't do that - there're no C++ flavor classes in IDL. If you want to return an object of some class from a function you have to declare an interface and possibly a coclass (the latter may not be required depending on your sitiation) and make the function return that interface.
I have a bit of a complex program which is giving me this apparently phantom error...
I'll start explaining with the help of this little example program I rigged that can throw my beautiful exception for anyone who runs it.
<!-- language: c# -->
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespace so_redux {
static class Program {
[STAThread]
static void Main(){
CS2JS _class=new CS2JS();
}
}//class Program
class CS2JS{
public CS2JS(){
Func<String,Object> js_eval=initJS();
Object cs_ic=initCS();
string xc;
object res;
cs_ic.GetType().GetMethod("init").Invoke(cs_ic,null);
AppDomain.CurrentDomain.SetData("trespasser",cs_ic);
xc=#"function edata(fieldname:String,ival:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var v1=sob.GetType().GetField(fieldname).GetValue(sob);
function HASH(s1:String,s2:String):Object{
var q1=sob.GetType().GetField(s1).GetValue(sob);
return q1.ITEM(s2);
}
var v2=v1.ITEM(ival);
return eval(v2);
}
edata('HT','foo');";
res=js_eval(xc);
// var xx;xx=new Hashtable();xx['sda']='1';eval(xx['sda']); OK
}
Func<String,Object> initJS(){
System.CodeDom.Compiler.CodeDomProvider jcc;
System.CodeDom.Compiler.CompilerParameters jcp;
System.CodeDom.Compiler.CompilerResults jcr;
System.Reflection.Assembly jas;
object jis;
string code;
Type t_ii;
code=#"#set #debug(off)
import System;
import System.Collections;
import System.Collections.Generic;
package internal_namespace{class internal_class{
public function internal_method(_code:String):Object{
return eval(_code);
}
}
}";
jcc=Microsoft.JScript.JScriptCodeProvider.CreateProvider("JScript");
jcp=new System.CodeDom.Compiler.CompilerParameters();
jcp.CompilerOptions="/fast-";
jcp.GenerateExecutable=false;
jcp.GenerateInMemory=true;
jcp.IncludeDebugInformation=false;
jcp.ReferencedAssemblies.Add("System.dll");
jcp.ReferencedAssemblies.Add("System.Core.dll");
jcp.WarningLevel=4;
jcr=jcc.CompileAssemblyFromSource(jcp,code);
jas=jcr.CompiledAssembly;
jis=jas.CreateInstance("internal_namespace.internal_class");
t_ii=jas.GetType("internal_namespace.internal_class");
return (s1)=>t_ii.InvokeMember("internal_method",System.Reflection.BindingFlags.InvokeMethod,null,jis,new object[]{s1});
}//initJS
Object initCS(){
var v1= Microsoft.CSharp.CSharpCodeProvider.CreateProvider("CSharp");
System.CodeDom.Compiler.CompilerParameters v2=new System.CodeDom.Compiler.CompilerParameters();
v2.GenerateExecutable=false;
v2.GenerateInMemory=true;
v2.IncludeDebugInformation=false;
v2.WarningLevel=4;
v2.ReferencedAssemblies.Add("System.dll");
v2.ReferencedAssemblies.Add("System.Core.dll");
string _code="public Hashtable2 HT;"+
"public void init(){"+
"HT=new Hashtable2();"+
"HT[\"foo\"]=\"1\";"+
"HT[\"bar\"]=\"HASH('HT','foo')\";"+
"}";
var v3="using System;using System.Collections;using System.Collections.Generic;"+
"namespace internal_namespace{public class Hashtable2:Hashtable{"+
"public Hashtable2():base(){} public Hashtable2(int N):base(N){}"+
"public Object ITEM(Object K){return this[K];} }"+
"[Serializable]public class internal_class{"+
"public internal_class(){}"+
_code+
"\n}}";
var v4=v1.CompileAssemblyFromSource(v2,v3);
var v5=v4.CompiledAssembly;
var v6=v5.GetType("internal_namespace.internal_class");
var v7=v5.CreateInstance("internal_namespace.internal_class");
return v7;
}//initCS
}//class CS2JS
}//namespace so_redux
The exception that is thrown is "index out of bounds", and it's thrown from JScript. The problem? It's that there is no array!
What this code is doing: first a JScript interpreter is initialized by compiling at runtime a class that "exports" an eval (one could do a dll, but in this case I didn't).
Then a C# assembly is compiled, an assembly that "exports" some user code (the variable _code in initCS is originally loaded by reading a text file).
After the initialization of the newly compiled class (the invoking of init()), I need the two assemblies (JScript and C#) to interact, so I need to pass data between them, and I thought of using AppDomain.
Note: in the C# assembly an Hashtable2 is defined because I put in there an ITEM method that one can use in alternative to the common property this[]: in this way debugging is easier (for examply by showing a holy MessageBox when accessing the values).
So, I pass the class instantiated in initCS to JScript, and JScript reads the internal Hashtable (HT). What I need to do is evaluate the data in the Hashtable, because it is supposed to be able to alter itself dynamically.
Everything works fine if I eval a string not taken from the Hashtable -- in the moment I take whatever is in the Hashtable and pass it to eval, then exceptions happen. Attention: the strings are absolutely the same (even comparing them with Equals) and they work, the difference is only from where they come from.
When the JScript function edata evals a string taken from the Hashtable, JScript says "index out of bounds", but as I was saying: I don't see any array there... (and maybe the problem is exactly that, dunno).
I admit I have my limitations in JScript, so if anybody could lend a hand to help understand WTF is going on, I would be really happy.
Temporary solution/workaround splitting the JScript function:
xc=#"function odata(fieldname:String,ival:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var v1=sob.GetType().GetField(fieldname).GetValue(sob);
return v1.ITEM(ival);
}
odata('HT','bar');";
res=js_eval(xc);
xc=#"function HASH(s1:String,s2:String):Object{
var sob=System.AppDomain.CurrentDomain.GetData('trespasser');
var q1=sob.GetType().GetField(s1).GetValue(sob);
return q1.ITEM(s2);
}
eval("+res.ToString()+");";
res=js_eval(xc);
but if anybody really got any idea of why is wrong in the first example, please explain me!
As new to groovy...
I'm trying to replace the java idiom for event listeners, filters, etc.
My working code in groovy is the following:
def find() {
ODB odb = ODBFactory.open(files.nodupes); // data nucleus object database
Objects<Prospect> src = odb.getObjects(new QProspect());
src.each { println it };
odb.close();
}
class QProspect extends SimpleNativeQuery {
public boolean match(Prospect p) {
if (p.url) {
return p.url.endsWith(".biz");
}
return false;
}
}
Now, this is far from what I'm used to in java, where the implementation of the Query interface is done right inside the odb.getObjects() method. If I where to code "java" I'd probably do something like the following, yet it's not working:
Objects<Prospect> src = odb.getObjects( {
boolean match(p) {
if (p.url) {
return p.url.endsWith(".biz");
}
return false;
}
} as SimpleNativeQuery);
Or better, I'd like it to be like this:
Objects<Prospect> src = odb.getObjects(
{ it.url.endsWith(".biz") } as SimpleNativeQuery
);
However, what groovy does it to associate the "match" method with the outer script context and fail me.
I find groovy... groovy anyways so I'll stick to learning more about it. Thanks.
What I should've asked was how do we do the "anonymous" class in groovy. Here's the java idiom:
void defReadAFile() {
File[] files = new File(".").listFiles(new FileFilter() {
public boolean accept(File file) {
return file.getPath().endsWith(".biz");
}
});
}
Can groovy be as concise with no additional class declaration?
I think it would have helped you to get answers if you'd abstracted the problem so that it didn't rely on the Neodatis DB interface -- that threw me for a loop, as I've never used it. What I've written below about it is based on a very cursory analysis.
For that matter, I've never used Groovy either, though I like what I've seen of it. But seeing as no one else has answered yet, you're stuck with me :-)
I think the problem (or at least part of it) may be that you're expecting too much of the SimpleNativeQuery class from Neodatis. It doesn't look like it even tries to filter the objects before it adds them to the returned collection. I think instead you want to use org.neodatis.odb.impl.core.query.criteria.CriteriaQuery. (Note the "impl" in the package path. This has me a bit nervous, as I don't know for sure if this class is meant to be used by callers. But I don't see any other classes in Neodatis that allow for query criteria to be specified.)
But instead of using CriteriaQuery directly, I think you'd rather wrap it inside of a Groovy class so that you can use it with closures. So, I think a Groovy version of your code with closures might look something like this:
// Create a class that wraps CriteriaQuery and allows you
// to pass closures. This is wordy too, but at least it's
// reusable.
import org.neodatis.odb.impl.core.query.criteria;
class GroovyCriteriaQuery extends CriteriaQuery {
private final c;
QProspect(theClosure) {
// I prefer to check for null here, instead of in match()
if (theClosure == null) {
throw new InvalidArgumentException("theClosure can't be null!");
}
c = theClosure;
}
public boolean match(AbstractObjectInfo aoi){
//!! I'm assuming here that 'aoi' can be used as the actual
//!! object instance (or at least as proxy for it.)
//!! (You may have to extract the actual object from aoi before calling c.)
return c(aoi);
}
}
// Now use the query class in some random code.
Objects<Prospect> src = odb.getObjects(
new GroovyCriteriaQuery(
{ it.url.endsWith(".biz") }
)
)
I hope this helps!
I believe your real question is "Can I use closures instead of anonymous classes when calling Java APIs that do not use closures". And the answer is a definite "yes". This:
Objects<Prospect> src = odb.getObjects(
{ it.url.endsWith(".biz") } as SimpleNativeQuery
);
should work. You write "However, what groovy does it to associate the "match" method with the outer script context and fail me". How exactly does it fail? It seems to me like you're having a simple technical problem to get the solution that is both "the groovy way" and exactly what you desire to work.
Yep, thanks y'all, it works.
I also found out why SimpleNativeQuery does not work (per Dan Breslau).
I tried the following and it worked wonderfully. So the idiom does work as expected.
new File("c:\\temp").listFiles({ it.path.endsWith(".html") } as FileFilter);
This next one does not work because of the neodatis interface. The interface does not enforce a match() method! It only mentions it in the documentation yet it's not present in the class file:
public class SimpleNativeQuery extends AbstactQuery{
}
Objects<Prospect> src = odb.getObjects(
{ it.url.endsWith(".biz") } as SimpleNativeQuery
);
In the above, as the SimpleNativeQuery does not have a match() method, it makes it impossible for the groovy compiler to identify which method in the SimpleNativeQuery should the closure be attached to; it then defaults to the outer groovy script.
It's my third day with groovy and I'm loving it.
Both books are great:
- Groovy Recipes (Scott Davis)
- Programming Groovy (Venkat Subramaniam)