I am an experienced C programmer, learning C++ by writinging a
mathematical toolkit in the framework of a script interpreter. I am
posting here to ask for advice (or references) on the object design
and implimentation.
Currently I have a portable "ScriptSess ion" class which contains the
mechanics of looping with a user prompt, parsing a sentence and
handling syntax errors, etc., and I wan this to be a class I can use
for any script interpreter.
One of the core functions is the execution of a command sentence. This
necessarily involves some mathematical commands which should not be
part of "ScriptSess ion" so I started by overloading a method called
interpret, which is virtual in the base class:
class ScriptSession
{
public:
...
virtual bool ScriptSession:: execute(void);
}
I have then written a method within the final application which
overload this, but it needs to know a lot about the internals of the
ScriptSession class so it has become rather ugly and feels like it is
voilating encpasulation and so on. Also, I have put everything in
here, even basic stuff like interpretation of the command "exit" which
is universal, so that won't do.
I bought "Design Patterns" (Gang of Four) but none of the patterns
seem to really fit this nicely. Or maybe I'm just missing some of the
important stuff. I apologise if I haven't explained the problem
clearly enough; that's part of the problem of course.
Any advice would be appreciated. Thanks,
Ian Giblin. 4 1981
Ian Giblin wrote: I am an experienced C programmer, learning C++ by writinging a mathematical toolkit in the framework of a script interpreter. I am posting here to ask for advice (or references) on the object design and implimentation.
The first thing to recommend that comes to mind is comp.object
newsgroup. OO Design has common principles that are not necessarily
language-specific. Check it out.
Currently I have a portable "ScriptSess ion" class which contains the mechanics of looping with a user prompt, parsing a sentence and handling syntax errors, etc., and I wan this to be a class I can use for any script interpreter.
One of the core functions is the execution of a command sentence. This necessarily involves some mathematical commands which should not be part of "ScriptSess ion" so I started by overloading a method called interpret, which is virtual in the base class:
class ScriptSession { public: ... virtual bool ScriptSession:: execute(void);
I thought you said "a method called interpret"... And a small note on
C++ syntax: you don't need a fully qualified name in a class definition.
You usually write
virtual bool execute();
(oh, yes, 'void' is also superfluous).
}
I have then written a method within the final application which overload this,
The correct term is "overrides" .
but it needs to know a lot about the internals of the ScriptSession class so it has become rather ugly and feels like it is voilating encpasulation and so on.
Yes, it rather sounds like a bad design.
Also, I have put everything in here, even basic stuff like interpretation of the command "exit" which is universal, so that won't do.
Well, without seeing more of your 'ScriptSession' class (at least its
interface, the implementation probably doesn't matter much) it is not
clear what you mean that it needs to know and what exactly are those
"internals" . Can't you provide access to those internals through some
protected functions?
I bought "Design Patterns" (Gang of Four) but none of the patterns seem to really fit this nicely. Or maybe I'm just missing some of the important stuff. I apologise if I haven't explained the problem clearly enough; that's part of the problem of course.
"Design Patterns" is by no means a "recipes for all occasions" type of
book. You learn the most common ones so you can recognise patterns in
your own code and describe them and later apply them.
Any advice would be appreciated. Thanks, Ian Giblin.
Well, take a look at comp.object and possibly ask them for an example
of an interpreter framework that you could extend. Perhaps somebody
here knows about it too (I don't), my colleagues whenever an interpreter
is needed all wrote their own, which seems like an overkill, but that's
up to them.
Shake the Web (or google for "interprete r C++ framework"), see if
something falls out. I bet other folks have written something in that
area. While it is a good idea to write one for training, it isn't so
good to get stuck on design when your actual goal is the language.
Take a look at "Advanced C++. Programming Styles and idioms" by James
Coplien. It's relatively old, but it's a good from design point of
view. Helped me to figure some C++ stuff out. It assumes you know C++
to some extend, of course.
Good luck! If you decide to continue trying to figure out your stuff
here, in comp.lang.c++, I strongly recommend making more specific
questions, a generic topic like "I want to create an interpreter and I
am stuck, help!" calls for a book rather than a newsgroup message.
V
Ian Giblin wrote: I bought "Design Patterns" (Gang of Four) but none of the patterns seem to really fit this nicely. Or maybe I'm just missing some of the important stuff. I apologise if I haven't explained the problem clearly enough; that's part of the problem of course.
Dr. Phlip Rx's /Refactoring to Patterns/ by Josh Kerievsky.
--
Phlip http://industrialxp.org/community/bi...UserInterfaces
Thanks for the detailed response.
Victor Bazarov <v.********@com Acast.net> wrote in message news:<1drld.333 765$wV.15439@at tbi_s54>... I thought you said "a method called interpret"...
Sorry. It annoys *me* when people make weird mistakes like that. So
now, I'm annoyed with myself for not spotting it when I check the
post.
And a small note on C++ syntax: you don't need a fully qualified name in a class definition. You usually write
virtual bool execute();
(oh, yes, 'void' is also superfluous).
<gulp> I see... I'll probably keep the 'void' because it reminds me
when I'm reading the code, but the class name prefix was a bit silly.
I'll take your other comments to heart. I will see how far I get with
this and ask on the object-oriented group if I cannot come up with a
good framework.
Regards, Ian.
Ian,
Its a bit hard to understand your problem, you've not posted
much code or information to work on.
However, you might want to look at TCL. Although this is implemented
in C ( I think), the basic model might be useful. TCL has a very regular
syntax so its easy to write an interpreter which can recognize the "command"
from the "options" and "data". Its then quite easy to add new commands
by writing a C/C++ package which implements the necessary pieces required
to register and execute the command. TCL provides the basic looping and
waiting for commands, then parses, checks for errros, and executes each
command or script you
pass in. TCL has a fairly complex API for accessing the guts of the
interpreter
and for implementing commands.
Python is also a model you could look at, as I remember, it was quite easy
to write an extension
(package of commands) to python in C/C++ ( or anything other language for
that matter ) and
load them into the python interpreter.
Hope that helps, and good luck.
dave
"Ian Giblin" <gi****@panix.c om> wrote in message
news:96******** *************** ***@posting.goo gle.com... I am an experienced C programmer, learning C++ by writinging a mathematical toolkit in the framework of a script interpreter. I am posting here to ask for advice (or references) on the object design and implimentation.
Currently I have a portable "ScriptSess ion" class which contains the mechanics of looping with a user prompt, parsing a sentence and handling syntax errors, etc., and I wan this to be a class I can use for any script interpreter.
One of the core functions is the execution of a command sentence. This necessarily involves some mathematical commands which should not be part of "ScriptSess ion" so I started by overloading a method called interpret, which is virtual in the base class:
class ScriptSession { public: ... virtual bool ScriptSession:: execute(void); }
I have then written a method within the final application which overload this, but it needs to know a lot about the internals of the ScriptSession class so it has become rather ugly and feels like it is voilating encpasulation and so on. Also, I have put everything in here, even basic stuff like interpretation of the command "exit" which is universal, so that won't do.
I bought "Design Patterns" (Gang of Four) but none of the patterns seem to really fit this nicely. Or maybe I'm just missing some of the important stuff. I apologise if I haven't explained the problem clearly enough; that's part of the problem of course.
Any advice would be appreciated. Thanks, Ian Giblin. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: #pragma once |
last post by:
That's all we are expecting from programs written in the managed code;
Though a MVP advised not to say that, because after JIT compilation the
code runs in the native! Funny, isn't? That means scripting languages run in
the Host code and never in the native? That means scripting languages
are poorer than .NET in speed just because they are hosted by an
interpreter? What about .Net run time libraries? Can any one tell me the
differences?...
|
by: fernandez.dan |
last post by:
Hey I'm sorry if this is not the appropriate news group for this
question. I was wondering if anyone has any recommendation for
embbedding a script engine in a c++ application. I want to feed my C++
application scripts which based on the script would create C++ objects
and call the appropriate methods.
At the moment I created a simple interpreter within our C++ aplication
that we can feed our custom scripts. The interpreter is primitive...
|
by: Smriti Dev |
last post by:
Hi There,
I'm creating a MS ACCESS database using Ms Access 2000 to store
Interpretation requests by different departments in a hospital and
Interpreter availability. All internal departments will be calling in or
faxing their Interpretation requests to Intake staff at the Interpretation
department and the intake staff will feed the request into the database.
However, their is one department, Rehab, that is going to be going to be
able...
|
by: HopfZ |
last post by:
Is there a way to make a (cross-browser) javascript function that will
open an existing webpage (for example, www.google.com) in a new window
(or in some part of _self) and then load a specified user script?
like this way:
openWithUserScript(
'http://www.google.com',
'http://www.my_homepage.com/my_script.js'
);
|
by: Alan Isaac |
last post by:
I'm fairly new to Python and I've lately been running a script at
the interpreter while working on it. Sometimes I only want to
run the first quarter or half etc. What is the "good" way to do this?
Possible ugly hacks include:
- stick an undefined name at the desired stop point
- comment out the last half
I do not like these and assume that I have overlooked the obvious.
| |
by: Joel |
last post by:
In the course of my project, I must include some custom logic and
would like to integrate a small script language in my application for
that purpose.
In C++, I used the LUA script language and I know that bindings exists
for a LUA/c# integration, but only using the binary DLL.
However, I would prefer a native c# solution and for a small language,
not a huge interpreter like Python.
Has anybody seen such implementation ?
Thanks,
|
by: uzzi |
last post by:
I don't know how to make a php script to work via cron...I want to make it run daily...My server API is CGI/Fast CGI.I have hosting from godaddy and in the help section i found that i have to specify the interpreter manually...look what it says:
i've tried with /web/cgi-bin/php "$HOME/html/path/to/my/script.php as command and it doesn't work.
if i run the script in browser it works...what should i introduce as a command..and do i have...
|
by: jkimbler |
last post by:
As part of our QA of hardware and firmware for the company I work for,
we need to automate some testing of devices and firmware. Since not
everybody here knows C#, I'm looking to create a new scripting
language that makes writing automated tests simpler. Really, I'm
looking to kind of abstract the power of the C# language into a
simpler language that's easier to learn. The script files would be
interpreted by a script interpreter...
|
by: Chris8Boyd |
last post by:
I am embedding Python in a MSVC++ (2005) application. The application
creates some environment and then launches a Python script that will
call some functions exported from the MSVC++ application.
I want to be able to debug the Python script by using a debug server,
like Winpdb (winpdb.org).
I use ActivePython 2.5.2.2, Microsoft Visual Studio 2005, and Winpdb
1.3.8.
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
| |
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
|
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| | |