Lesson plan
Conditional compilation
In computer programming, conditional compilation is a compilation technique which results in differing executable programs depending on parameters specified. This technique is commonly used when these differences in the program are needed to run it on different platforms, or with different versions of required libraries or hardware. Many programming languages support conditional compilation. Typically compiler directives define or "undefine" certain variables; other directives test these variables and modify compilation accordingly. For example, not using an actual language, the compiler may be set to define "Macintosh" and undefine "PC", and the code may contain: (* System generic code *) if mac != Null then (* macOS specific code *) else if pc != Null (* Windows specific code *) In C and some languages with a similar syntax, this is done using an '#ifdef' directive. A similar procedure, using the name "conditional comment", is used by Microsoft Internet Explorer from version 5 to 9 to interpret HTML code. There is also a similar proprietary mechanism for adding conditional comments within JScript, known as conditional compilation.
Article summary
In computer programming, conditional compilation is a compilation technique which results in differing executable programs depending on parameters specified. This technique is commonly used when these differences in the program are needed to run it on different platforms, or with different versions of required libraries or hardware. Many programming languages support conditional compilation. Typically compiler directives define or "undefine" certain variables; other directives test these variables and modify compilation accordingly. For example, not using an actual language, the compiler may be set to define "Macintosh" and undefine "PC", and the code may contain: (* System generic code *) if mac != Null then (* macOS specific code *) else if pc != Null (* Windows specific code *) In C and some languages with a similar syntax, this is done using an '#ifdef' directive. A similar procedure, using the name "conditional comment", is used by Microsoft Internet Explorer from version 5 to 9 to interpret HTML code. There is also a similar proprietary mechanism for adding conditional comments within JScript, known as conditional compilation.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.