OS_module

Classes for operating system services, and assorted other things. More...

Modules
	OS_module_internal_classes
	Internal OS_module classes and functions.

Classes
class	casacore::CanonicalConversion
	LDOUBLE is 8 bytes on SUN, but 16 bytes canonical. More...
class	casacore::CanonicalDataConversion
	A class with virtual functions to convert canonical format. More...
class	casacore::Conversion
	A class with general conversion definitions. More...
class	casacore::DataConversion
	Abstract base class with functions to convert any format. More...
class	casacore::Directory
	Get information about, and manipulate directories. More...
class	casacore::DirectoryIterator
	Traverse the contents of a directory. More...
class	casacore::DOos
	DO for accessing os-specific functions. More...
class	casacore::DynLib
	Class to handle loading of dynamic libraries. More...
class	casacore::EnvironmentVariable
	This class allows for getting enviroment variables. More...
class	casacore::File
	Class to get file information and a base for other file classes. More...
class	casacore::HostInfo
	Miscellaneous information about this host and process. More...
class	casacore::IBMConversion
	A class with static functions to convert IBM format. More...
class	casacore::IBMDataConversion
	A class with virtual functions to convert IBM format. More...
class	casacore::LECanonicalConversion
	A class with static functions to convert little endian canonical format. More...
class	casacore::LECanonicalDataConversion
	A class with virtual functions to convert little endian canonical format. More...
class	casacore::LittleEndianConversion
	A class with static functions to convert littleEndian format. More...
class	casacore::Memory
	Memory related information and utilities. use visibility=export> More...
class	casacore::MemoryTrace
	memory usage tracing mechanism More...
class	casacore::MemoryTraceBlock
	Class to write begin and end block message. More...
class	casacore::ModcompConversion
	Static functions to convert Modcomp numeric formats. More...
class	casacore::ModcompDataConversion
	A DataConversion class to convert between Modcomp format. More...
class	casacore::Path
	Path name of a file. More...
class	casacore::PrecTimer
	Precision timer to measure elapsed times in a cumulative way. More...
class	casacore::RawDataConversion
	A class with virtual functions to copy without conversion. More...
class	casacore::RegularFile
	Manipulate and get information about regular files. More...
class	casacore::SymLink
	Get information about, and manipulate symbolic links. More...
class	casacore::Time
	date and time enquiry functions, with some operations. More...
class	casacore::Timer
	measure the time it takes to execute parts of a program More...
class	casacore::VAXConversion
	A class with static functions to convert VAX format. More...
class	casacore::VAXDataConversion
	A class with virtual functions to convert VAX format. More...

Detailed Description

Classes for operating system services, and assorted other things.

See below for an overview of the classes in this module.

Prerequisite

• Nothing special

Review Status

Reviewed By:

Paul Shannon

Date Reviewed:

1995/06/02/

Etymology

'OS' is the standard abbreviation for 'Operating System'.

Synopsis

This module's main purpose is to provide convenient and uniform access to operating system features: environment variables, file and directory access, time and date services, and uniform data representation (which solves the variety of ways the fundamental data types are represented in hardware).

The following functionality is available:

• Class EnvironmentVariable for access to environment variables.
• Class Path, RegularFile, SymLink, and Directory for dealing with the file system. Note that module IO deals with reading and writing data to files and other IO streams.
• Class Time to get the system time.
• Class Timer to measure elapsed, user, and system time of a piece of code.
• Framework Conversion to convert data from one format to another. There are classes to convert to/from canonical format, VAX format, and IBM/360 format. The structure of the framework is shown in the OMT diagram.
• A class to encapsulate Memory usage. Class MemoryTrace makes it possible to trace all memory (de)allocations through malloc and free (new and delete). It only works on Linux systems though.

Example

See the various class header files.

Motivation

We want to provide a simple and uniform interface to OS services and features for the application and library programmer. To pick a few examples:

1. Recursive deletion of a directory.
2. Access to time and date information.
3. Get and set environment variables.

To Do

• The OS module is a bit fuzzy: for example, canonical data format conversion is more a matter of hardware than of operating system differences. Perhaps these particular classes should be moved to a new module.
• Time and Date classes should be revised after studying similar classes designed by others. Roel Martinez is tenatively scheduled to do this in the late summer of 1995.
• There was once some discussion of a 'VOS' (virtual operating system) module. This seems like a good idea. Nested subdirectories for specific operating systems would contain the implementations, but a common interface would be used for all. And perhaps local site makedefs could be used to select the proper implementation to link against, with no special action required of the programmer.