Skip to content

separate-compilation.md

Latest commit

 

History

History
106 lines (64 loc) · 3.79 KB

separate-compilation.md

File metadata and controls

106 lines (64 loc) · 3.79 KB
Raw

C++ compilation model: Separate Compilation {#separate-comp}

Skeleton descriptions are typeset in italic text, so please don't remove these descriptions when editing the topic.

Overview

Provides a short natural language abstract of the module’s contents. Specifies the different levels of teaching.

This module outlines the issues involved in using separate compilation on multiple program files.

Level Objective

Foundational: Awareness of the existence of separate compilation

Main: Awareness of supporting mechanisms and tools

Advanced: Awareness of technicalities and tools

Motivation

Why is this important? Why do we want to learn/teach this topic?

Any non-trivial program will span more than one source file. This makes separate compilation necessary. Separate compilation also leads to quick build times in projects under development.

Topic introduction

Very brief introduction to the topic.

Foundational: Using

Background/Required Knowledge

A student:

  1. needs to have the text editor skills to split a single-file program into multiple files.
  2. needs to be able to split function and classes into their declaration and definition. [C++ object model: declarations] [C++ object model: Definitions]

Student outcomes

A list of things "a student should be able to" after the curriculum. The next word should be an action word and testable in an exam. Max 5 items.

A student should be able to:

  1. split a single file program into main, one or more auxiliaries, and header files (or modules), all in one directory
  2. compile and link a program that is spread over multiple files (again, all in one directory), either on the commandline or with a build system.
  3. describe the functions of the various files involved: source, object, executable.

Points to cover

  • Necessity of having function be declared at the locus of use
  • Solving this by explicit declaration or by using header files.

Caveats

This section mentions subtle points to understand, like anything resulting in implementation-defined, unspecified, or undefined behavior.

  1. Explain differences (including in desirability) between having explicit declarations of functions in the main program versus using header files or modules.
  2. Compilation on a single commandline versus multiple. Resolution order when linking.
  3. What needs to be recompiled if only a function is altered? Altered in use syntax versus altered only in semantics.

Main: implementing

Background/Required Knowledge

  • All of the above.

Student outcomes

A student should be able to:

  1. Use compile flags, including -I and -L to specify search paths.
  2. Make header files for their own code, including using header guards.
  3. Use include directives for the headers of external libraries.
  4. Be able to declare extern variables.

Caveats

  1. Build systems make things both easier and harder.

Points to cover

  • Cover the mechanisms for include and library paths to your own code, as well as discovery mechanisms for external libraries.

Advanced

These are important topics that are not expected to be covered but provide guidance where one can continue to investigate this topic in more depth.

  1. Language inter-operability: the extern "C" mechanism.
  2. Linker conventions including name mangling.
  3. The nm tool for inspection object files and libraries, including de-mangling.
  4. Understand the issues involved in deciding between include guards and #pragma once.