Groovy on VMS

[Arne Vajhøj]

Two more tech demo's.

VMS Tech Demo 14 - Groovy for scripting:
https://www.vajhoej.dk/arne/articles/vmstd14.html

Covering:
* basic scripting
* using to SYS$ and LIB$ functions
* accessing index-sequential files, databases and message queues

VMS Tech Demo 15 - Groovy for applications:
https://www.vajhoej.dk/arne/articles/vmstd15.html

Covering:
* Groovy calling Java
* Java calling Groovy
* Groovy calling C/Pascal/Basic
* C/Pascal/Basic calling Groovy

Arne

[Craig A. Berry]

Post by Arne Vajhøj
Two more tech demo's.
  https://www.vajhoej.dk/arne/articles/vmstd14.html

How does Groovy compare to BeanShell?

https://github.com/beanshell/beanshell

[Arne Vajhøj]

Post by Craig A. Berry

Post by Arne Vajhøj
Two more tech demo's.
   https://www.vajhoej.dk/arne/articles/vmstd14.html

How does Groovy compare to BeanShell?
https://github.com/beanshell/beanshell

Good question.

And I am not an expert on the topic.

But to my understanding then:
* they are relative similar in language syntax and features today
* they came from a very different (opposite) background:
- BeanShell started as Java interpreter and evolved
into a full script language with optional typing
- Groovy started as a Java-like scripting language
without typing that added typing later
* they are used for different purposes:
- BeanShell is very much used for JSR223 embedded
scripting language in Java applications
- Groovy got a much broader usage:
. web applications (Grails framework, Groovelets)
. more general scripting (the world dominated by
Perl and Python)
. JSR223 embedded scripting language in Java applications
* Groovy is more used than BeanShell - especially
Grails have a reasonable big user base

I have only used BeanShell as embedded script engine
for 100% Java compatible. I have dabbled in Groovy for both
web and scripting.

A job search at dice.com find 239 Groovy jobs and 0
BeanShell jobs. I am sure there are plenty of jobs
where BeanShell is used but its usage is not
important enough to warrant being mentioned in the ad.

Arne

[Arne Vajhøj]

Post by Arne Vajhøj
A job search at dice.com find 239 Groovy jobs and 0
BeanShell jobs. I am sure there are plenty of jobs
where BeanShell is used but its usage is not
important enough to warrant being mentioned in the ad.

Or to to rephrase: "Groovy developer" is a thing while
"BeanShell developer" is not a thing. BeanShell is a skill
like JDBC, JPA, JMS, JNI etc. for a "Java developer".

This is of course totally non-technicial. But it is
how the languages are perceived in the industry.

IMHO. YMMV.

Arne

[Simon Clubley]

Post by Arne Vajhøj

Post by Arne Vajhøj
A job search at dice.com find 239 Groovy jobs and 0
BeanShell jobs. I am sure there are plenty of jobs
where BeanShell is used but its usage is not
important enough to warrant being mentioned in the ad.

Or to to rephrase: "Groovy developer" is a thing while
"BeanShell developer" is not a thing. BeanShell is a skill
like JDBC, JPA, JMS, JNI etc. for a "Java developer".

$ set response/mode=good_natured

Hmmm, I wonder how many Java developers claiming JNI as a "skill"
could actually _use_ JNI (and make it work!) ? :-)

JNI requires a very different mindset and knowledge base than most
of the other Java development skills...

Simon.

[Arne Vajhøj]

Post by Simon Clubley

Post by Arne Vajhøj

Post by Arne Vajhøj
A job search at dice.com find 239 Groovy jobs and 0
BeanShell jobs. I am sure there are plenty of jobs
where BeanShell is used but its usage is not
important enough to warrant being mentioned in the ad.

Or to to rephrase: "Groovy developer" is a thing while
"BeanShell developer" is not a thing. BeanShell is a skill
like JDBC, JPA, JMS, JNI etc. for a "Java developer".

$ set response/mode=good_natured
Hmmm, I wonder how many Java developers claiming JNI as a "skill"
could actually _use_ JNI (and make it work!) ? :-)
JNI requires a very different mindset and knowledge base than most
of the other Java development skills...

True.

JNI is tricky (read: it sucks).

But in 5-10 years JNI will hopefully be replaced by
Foreign Function.

Arne

[Lawrence D'Oliveiro]

Post by Arne Vajhøj
JNI is tricky (read: it sucks).

I managed to do some stuff in Android with it, back in the day. I
created a Python script
<https://bitbucket.org/ldo17/jniglue/src/master/> that generates
slightly more convenient wrappers around the entry points in the
JNIEnv object, e.g. for the NewStringUTF method:

static inline jstring JNNewStringUTF(JNIEnv* env, const char* a1)
{
return
(**env).NewStringUTF(env, a1);
} /*NewStringUTF*/

so you call it like this:

const jstring msgobj = JNNewStringUTF(env, usebuf);

I felt it made things much more bearable.

[Arne Vajhøj]

Post by Lawrence D'Oliveiro

Post by Arne Vajhøj
JNI is tricky (read: it sucks).

I managed to do some stuff in Android with it, back in the day. I
created a Python script
<https://bitbucket.org/ldo17/jniglue/src/master/> that generates
slightly more convenient wrappers around the entry points in the
static inline jstring JNNewStringUTF(JNIEnv* env, const char* a1)
{
return
(**env).NewStringUTF(env, a1);
} /*NewStringUTF*/
const jstring msgobj = JNNewStringUTF(env, usebuf);
I felt it made things much more bearable.

That converts the C++ API to a C API, but there is more
hassle in JNI than that.

Arne

PS: (**env).Foobar is rather unusual - the common style is
(*env)->Foobar.

[Lawrence D'Oliveiro]

That converts the C++ API to a C API ...

No, it’s all strictly C.

PS: (**env).Foobar is rather unusual - the common style is
(*env)->Foobar.

I don’t understand why. It’s the same number of characters either way.

[Arne Vajhøj]

Post by Lawrence D'Oliveiro

That converts the C++ API to a C API ...

No, it’s all strictly C.

Your code is C. And I suspect the JNI code being called is C as well.

But I consider:

o->f(a1, a2, a3) to be C++
f(o, a1, a2, a3) to be C
o->f(o, a1, a2, a3) to be C++ API in C language

Post by Lawrence D'Oliveiro

PS: (**env).Foobar is rather unusual - the common style is
(*env)->Foobar.

I don’t understand why. It’s the same number of characters either way.

True. But if you look at examples in documentation and elsewhere, then ...

Arne

[Lawrence D'Oliveiro]

Post by Arne Vajhøj
o->f(a1, a2, a3) to be C++

If you can refer to o as “this”, that’s C++. You can’t do that in C.

Learn to tell the difference.

[Arne Vajhøj]

Post by Lawrence D'Oliveiro

Post by Arne Vajhøj
o->f(a1, a2, a3) to be C++

If you can refer to o as “this”, that’s C++. You can’t do that in C.

But this is not available by magic. It is there because
it (at least in some implementations - I doubt that the
standard define the "how") pass it as a hidden 1st argument.

Arne

[Arne Vajhøj]

Post by Arne Vajhøj

Post by Lawrence D'Oliveiro

Post by Arne Vajhøj
o->f(a1, a2, a3) to be C++

If you can refer to o as “this”, that’s C++. You can’t do that in C.

But this is not available by magic. It is there because
it (at least in some implementations - I doubt that the
standard define the "how") pass it as a hidden 1st argument.

To illustrate:

$ type m.cxx
#include <iostream>

using namespace std;

class C
{
public:
virtual void M1(int v) = 0; // C++ API in C++
virtual void M2(char *s) = 0; // C++ API in C++
};

class C1 : public C
{
public:
void M1(int v) { cout << "C1 says: " << v << endl; }
void M2(char *s) { cout << "C1 says: " << s << endl; }
};

class C2: public C
{
public:
void M1(int v) { cout << "C2 says: " << v << endl; }
void M2(char *s) { cout << "C2 says: " << s << endl; }
};

extern "C"
{
void f(C **o);
}

int main()
{
C *o1 = new C1();
f(&o1);
delete o1;
C *o2 = new C2();
f(&o2);
delete o2;
return 0;
}

$ type s.c
#include <stdio.h>

struct C;

typedef void (*fptr1)(struct C **this, int v); // C++ API in C
typedef void (*fptr2)(struct C **this, char *s); // C++ API in C

struct C_vtable
{
fptr1 M1;
fptr2 M2;
};

struct C
{
struct C_vtable *vtable;
};

void f(struct C **o)
{
(*o)->vtable->M1(o, 123);
(*o)->vtable->M2(o, "ABC");
}
$ cxx m
$ cc s
$ cxxlink m + s
$ run m
C1 says: 123
C1 says: ABC
C2 says: 123
C2 says: ABC

Arne

[Chris Townley]

Arne

As others have said - Don't feed the troll, especially when he turns
into a nasty b*stard

[Lawrence D'Oliveiro]

Post by Arne Vajhøj

Post by Lawrence D'Oliveiro

Post by Arne Vajhøj
o->f(a1, a2, a3) to be C++

If you can refer to o as “this”, that’s C++. You can’t do that in C.

But this is not available by magic.

It’s part of the language. That’s one way to tell that it’s C++ and not C.

[Craig A. Berry]

Post by Arne Vajhøj

Post by Craig A. Berry

Post by Arne Vajhøj
Two more tech demo's.
   https://www.vajhoej.dk/arne/articles/vmstd14.html

How does Groovy compare to BeanShell?
https://github.com/beanshell/beanshell

Good question.
And I am not an expert on the topic.
* they are relative similar in language syntax and features today
  - BeanShell started as  Java interpreter and evolved
    into a full script language with optional typing
  - Groovy started as a Java-like scripting language
    without typing that added typing later
  - BeanShell is very much used for JSR223 embedded
    scripting language in Java applications
    . web applications (Grails framework, Groovelets)
    . more general scripting (the world dominated by
      Perl and Python)
    . JSR223 embedded scripting language in Java applications
* Groovy is more used than BeanShell - especially
  Grails have a reasonable big user base
I have only used BeanShell as embedded script engine
for 100% Java compatible. I have dabbled in Groovy for both
web and scripting.

That makes sense. I don't do much with Java very often and I've never
encountered Groovy in the wild; I've only encountered BeanShell once and
it was embedded in an app specifically for making that app's
capabilities scriptable, so even my very limited experience is
consistent with yours.

[Arne Vajhøj]

Post by Arne Vajhøj
Two more tech demo's.
  https://www.vajhoej.dk/arne/articles/vmstd14.html
* basic scripting
* using to SYS$ and LIB$ functions
* accessing index-sequential files, databases and message queues
  https://www.vajhoej.dk/arne/articles/vmstd15.html
* Groovy calling Java
* Java calling Groovy
* Groovy calling C/Pascal/Basic
* C/Pascal/Basic calling Groovy

The third to complete the Groovy demos.

https://www.vajhoej.dk/arne/articles/vmstd16.html

VMS Tech Demo 16 - Groovy for web

Covering:
* web services (SOAP, XML-RPC, REST)
* CGI scripts
* Groovelets
* Grails

Most of it is actually copied either in slightly modified
version or as is from other articles, so it is more an extract
of Groovy stuff from multiple articles than it is new
material.

Arne