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Explains code organization, provides coding guidelines, and other information relevant to Trafodion code development.

Code Organization

To be written.

C++ Guidelines

These are the C++ coding guidelines that are part of the acceptance criteria for code submitted to the Trafodion. Trafodion reviewers use these guidelines when reviewing changes.

 

The guidelines describe practices that are either required or preferred. In addition, areas where there is no preference between two or more practices are described.

 

Trafodion is composed of several distinct sub-projects, some of which have coding guidelines that differ from the Trafodion standard; for example, a requirement in most areas of the code may be only preferred in others.

 

There may also be existing code that violates one or more of the published requirements. The intent is to correct these over time, and corrections are encouraged when changing code to make a fix or implement new functionality. However, changes that are solely coding guideline changes are not recommended since this places undue burden on the reviewers.

 

Header Files

Keep #include directives to a minimum in header files.

 

You may forward declare classes and structs when the only use within the header file is a pointer or reference. While includes should be kept to a minimum, if something is used in a header file and cannot be forward declared, it must be explicitly included.

 

All files, headers and implementation, should include everything they need to be self-sufficient. They should never assume something will be pre-included. In other words, the contents of a header file should compile cleanly by itself. To help ensure this, all implementation files should include their respective header file first.

 

Header files should not contain declarations for public items that are only used by the implementation file. Public items that are require in the implementation file but not the header file should be declared in the implementation file. The preference is NOT to create header files that consist only of includes of other header files.

 

Declare as little as possible in the header file and keep as much of the actual implementation private as is reasonable. For instance, don’t include in a header file declarations of types, enums, and functions that are only referenced by the implementation file.

Including Standard Header Files

The preference is for C++ style includes over C style includes for standard header files.

//Preferred
#include <cstdio>

//Accepted
#include <stdio.h>

Include Guards

 

All header files must use include guards. The name of the include guard #define should be the filename in all uppercase, with underscore used in place of periods.

 

For instance, if the header file is named ServerInterface_ODBC.h, the header file should begin and end as follows:

#ifndef SERVERINTERFACE_ODBC_H
#define SERVERINTERFACE_ODBC_H
...
#endif /* SERVERINTERFACE_ODBC_H */
Comments following the #endif indicating the include guard are preferred.
 

Variable Declaration and Naming Standards

 

 

Trafodion uses a combination of Pascal and Camel case.

  • Pascal case means that the first letter in each word in an identifier is capitalized.
  • Camel case is similar except the first letter is in lower case.
 

 

For both, underscores are not used to separate words. The general rule is that identifiers with local scope start with a lower case letter and identifiers with global scope start with an upper case letter.

//Pascal case
class AuthenticationMessage;

//Camel case (aka lower Camel case or camelCase)
int logonCount;
Class Names
Class names should be Pascal case and should describe the object contents (not what it does), with as little abbreviation as possible. When names include acronyms, the acronyms should be in all upper case.
Acceptable Examples

 

//Preferred

class SQLSessionContext; // an object that contains the context for a SQL session
class PrivilegeList; // a list of privileges
Poor Examples
class OutputInfo; // Doesn't describe class contents, no context
class ReadTableDef; // Describes what class does, not contents
class Cmdline_Args; // Prefer Pascal case, no underscore, for class names

Class Member Variable Names

Private member data variables should be suffixed with an underscore and should use Camel case. When names include acronyms, the acronyms should be in all upper or all lower case, dependent on which case the first letter should be.

Example: Class Member Variable Names
class Employee
{
public:
   Employee ();
private:
   std::string firstName_;
   std::string lastName_;
   uint16_t    departmentNumber_;
   std::string departmentName_;
   uint32_t    irsSSN_;
}

Function Names

Class member functions and static file functions should use Camel case. External non-class functions should use Pascal case. Except for constructors, destructors, and operators, the function name should include a verb that describes the action the function is performing.

Good Examples

 

/Class member functions
int32_t getSalary() const;
int32_t setAuthID();
int32_t closeAllCursors();

 

Bad Examples

 

// Is it setting break enabled, returning it or ???
int32_t SQLCLI_BreakEnabled();

 

Enums

 

 

 

 

 


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