This OCX component has been discontinued. Please contact us if you have a need for this functionality.

Demo version and documentation

Click here to download the demo version with full documentation and help file.

Click here to download only the documentation.

Unique selling points

The current version of the expression evaluator is available in a .NET compatible OCX format, therefore usable from a variety of programming environments. But why would you buy this OCX?

1. Low cost; estimated development time of this component by a 3rd party based on user sessions, design, programming & project management estimates to 6 months

2. No specific knowledge required; you or your programmers don’t need to know anything about the underlying compiler technologies & theories

3. Fast; the component has been optimised in such a manner that calculating expressions, setting & getting variable values and other internal operations are fast. Performance is higher than what would ever be achievable in an environment like Visual BASIC.

4. Flexible; because all variables are stored in variants maximum flexibility is achieved for the end-user. Type-casting is handled internally by the expression evaluator and is as flexible as possible.

5. Standard functions; more than 70 extremely fast standard functions are available to the end-user without any required investments from your side

6. Reliable; proven & tested by customers in their applications

7. Good programming; audited by several other programmers which all concluded that the program has a good technological base

8. Basic & easy to use interface; the interface is designed in such a way that it fits in to most business applications easily. End-users find it easy to use. Expression rules are kept as simple as possible. All functionalities have visual clues. Please look at the following screenshot. 

9. Easy to distribute & install; The OCX comes in a redistributable EXE package which is easily installable by an end-user. Also, including OCX-es in your favourite set-up program (like InstallShield) is very easy.

10. Add your own functions and operators (called inline functions in the documentation). Remove standard functions and operators to completely define your own language. All operators have weights so you may influence the way the expression is calculated.

11. OnSyntaxError event. Generate your own error messages in the format required by your customer.

Source code licenses

The component is built in Borland Delphi version 7. The source codes are licensed to customers in a special license agreement. Please send us a mail for pricing and conditions.

Frequently asked questions

How do I install the expression evaluator on a customers system

First of all make sure the customer uses a 32-bit windows version. Then check if you or your company has the right to distribute the software. You best use the file supplied by QO to automatically extract and register the appropriate servers. If you want to include the OCX into your setup program make sure that the installation program registers the OCX with the operating system.

Manual installation of the file involves copying the file to the target system (for example to the c:\components folder), starting a command prompt and running regsvr32 on the OCX in the target folder. For example :

    regsvr32 QOExpressionEvaluatorV2.ocx

The system will notify you via a dialog box that the registration process was successful.

Where may I find the description of all properties, methods and events

You will find this in the word documentation delivered with your OCX. You may also consult the help file. Use the forward and back buttons to view all information.

Why can’t I enter statements like case or if .. then .. else into the expression box

The software you purchased is an expression evaluator. A expression never contains language contructions. Please look to scripting tools for this kind of functionality. If you really feel you can’t do without it please mail your request to qo@wsx.nl.

What should I do if I run into a problem

You should contact the reseller (mostly www.componentsource.com) you bought the component from. They can give you support on the product and know the answer to most questions. Support mails targeted towards qo@wxs.nl will be re-routed to the support desk of www.componentsource.com .

What is an expression

Good question. Formally it is defined as follows.

Expression are the fundamental means of specifiying computations in a programming language (that’s why there are no case or if … then .. else language constructions). The purpose of an arithmetic expression is to specify an arithmetic computation. An implementation of such a computation must cause 2 actions; fetching the operands, usually from memory, and executing the arithmetic operations on those operands. (quoted from Robert W Sebesta’s concepts of programming languages. ISBN 0-201-75295-6)

In the QO expression evaluator the result type of an expression is not fixed. This means that it may be for example a Boolean, an integer or a string. If you need to enforce a specific result type check the result type of the expression after the user has defined it.

When and how will I receive the next update?

Typically there will be one major update a year. There may be a few sub-releases per year containing customer requests. If you have purchased the 12 months support pack you will receive the updates via e-mail. If you have not purchased the support pack you will need to re-purchase the software to obtain the new version. You will also be notified if your support period ends so you will be able to purchase a next support period.