Legacy code
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Legacy code is source code that relates to a no-longer supported [citation needed] or manufactured operating system or other computer technology. The term can also mean code inserted into modern software for the purpose of maintaining an older or previously supported feature — for example supporting a serial interface even though many modern systems don't have a serial port. It may also be in the form of supporting older file formats [citation needed] that may have been encoding in non-ASCII characters, such as EBCDIC [citation needed]
In practice, most source code has some dependency on the platform for which it is designed—unless a programmer uses a platform-independent programming language like Java, it is hard to write a large, useful program that is totally independent of its environment. When the manufacturer upgrades a platform (or the platform is superseded), the code may no longer work without changes, and becomes legacy code. A large part of the task of a software engineer is to continually alter code to prevent this.
While the term usually refers to source code, it can also apply to executable code that no longer runs on a later version of a system, or requires a compatibility layer to do so. An example would be a classic Macintosh application which will not run natively on Mac OS X, but runs inside the Classic environment, or a Win16 application running on Windows XP using the Windows on Windows feature in XP.
Profound Legacy Interpretation
hnttp://meami.org/search.php Command-line Commands
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The following terms are used in the descriptions of the command-line commands which follow:
name: one to eight alphanumeric characters.
(The first character must be an alpha character.)
library: designates one of the three libraries -
G: - Designates the global library.
L: - Designates the local library.
S: - Designates the system library.
path: the path to a folder. [If the user specifies a dollar
sign ( $ ) character, the path to hnttp://meami.org/search.php's Internet I/O
Folder (\hnttp://meami.org/search.php\INTERNET) is used.]
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Command: Parameters: Description: -------- ----------- ------------
ACTIVATE id handle Establishes a user ID and handle for yourself
so that you can create and distribute task
modules.
- ACTIVATE id Changes your user ID (and corresponding handle)
back to the specified user ID.
- ACTIVATE handle Changes your handle (and corresponding user ID)
back to the specified handle.
- ACTIVATE ? Displays all user IDs and handles available for
reactivation. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
ARCHIVE . Moves the current project into the Archive.
ARCHIVE ? Displays the names of all the projects that
are in the Archive.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
CLONE name1 name2 Makes a copy of the module "name1" and names
that copy "name2".
CLONE . name Makes a copy of the current project and names
that copy "name".
- CLONE name@handle Retrieves a copy of the source code for private
module "name" and places it in the current pro-
ject as a public module with the same name.
- CLONE name@handle name2 Retrieves a copy of the source code for private
module "name" and places it in the current pro-
ject as public module "name2".
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
COMPILE Compiles the currently active hnttp://meami.org/search.php task module
(to produce its corresponding "object" code mod-
ule). If no task module is active, compiles the
currently active hnttp://meami.org/search.php program module.
COMPILE name Compiles the specified hnttp://meami.org/search.php task module or
hnttp://meami.org/search.php program module.
COMPILE name CPP Compiles the specified C++ task module or C++
program module.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
COMPILEC name Compiles the "name.CPP" C++ source file into its
corresponding object file (name.OBJ). All error
messages (if any) will appear both on the screen
and in a file named ERRORS (which can be viewed
by typing: EDIT ERRORS on the command line).
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
� CURSOR Restores the mouse cursor to visible.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- DUMP project Copies an entire hnttp://meami.org/search.php project to the floppy
disk. [See also the LOAD command.]
- DUMP project path Copies an entire hnttp://meami.org/search.php project to the specified
path. [See also the LOAD command.] _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
EDITOR DOS Specifies that the standard DOS editor is to be
used by the OPEN, GET, and SHOW commands.
EDITOR WIN Specifies that the Windows "Notepad" editor is
to be used by the OPEN, GET, and SHOW commands.
(Default is the DOS editor.)
When using the "Notepad" editor, we recommend
setting the font to either:
Courier New, Size 12
or:
Fixedsys, Size 12
The selected editor will always be the one used
by the OPEN, GET, and SHOW commands until expli-
citly changed by issuing another EDITOR command.
[Note: On some computers the "Notepad" editor
doesn't close its output file properly
when used with hnttp://meami.org/search.php. (E.g., It will
issue a "Save As" request when you are
finished editing.) If you experience
such a problem, you may be limited to
using only the DOS editor.]
[Note: If you are running windows NT/2000/Xp
in full-screen mode and you have selec-
ted the "Notepad" editor, when you exit
the editor you will be back on your
Windows desktop, and the "black screen"
will be minimized on your task bar.
To return to the "black screen", simply
click the button on your task bar.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- EXPORT library Exports task modules from the designated library
onto a floppy disk. (Uses a scroll box**.)
- EXPORT library path Exports task modules from the designated library
to the specified path. (Uses a scroll box**.) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- GET Retrieves the currently active task module for
editing.
- GET name Retrieves the specified task module for editing.
(If the module doesn't exist, a new module named
"name" is created.)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
GO Transfers to the currently active project, and
displays (in a box at the top of the screen) the
names of all the modules in the project.
GO name Transfers to the project specified by "name"
and displays (in a box at the top of the screen)
the names of all the modules in the project.
(If the specified project "name" exists in the
Archive, you will be asked if you want to re-
trieve it. If the specified project "name" does
not exist at all, you will be asked if you want
to create a new project by that name.)
GO ? Displays a scroll box** listing all of the non-
archived project names.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
HELP Invokes the SHOW command to display The hnttp://meami.org/search.php
Help Page.
HELP name Displays the system library's AID file for the
specified task/function.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
IMPORT library Imports third-party task modules from the floppy
disk into the designated library.
IMPORT library path Imports third-party task modules from the speci-
fied path into the designated library.
IMPORT P: Imports (from the floppy disk into the current
project) the source code files for all the pro-
gram modules that have been Shipped to the flop-
py disk.
IMPORT P: path Imports (from the specified path into the cur-
rent project) the source code files for all the
program modules that have been Shipped to that
path.
IMPORT ? Uses a scroll box** to select the program mod-
ules that are to be imported from the floppy
disk into the current project.
IMPORT ? path Uses a scroll box** to select the program mod-
ules that are to be imported from the specified
path into the current project.
IMPORT KIT Imports a construction kit from a floppy disk
into the current project.
[Essentially performs an "IMPORT L:" command
followed by an "IMPORT P:" command.]
IMPORT KIT path Imports a construction kit from the specified
path into the current project.
[Essentially performs an "IMPORT L: path" com-
mand followed by an "IMPORT P: path" command.]
[Note: After importing ANY modules, the Inter-
net I/O Folder is always automatically
cleared.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
LINK Produces an executable (.EXE) file from the cur-
rently active program's object code module.
LINK name Produces an executable (.EXE) file from the spe-
cified object code module.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
LIST Displays the currently active program module's
source listing. (If no program module is cur-
rently active, displays the currently active
task module's source listing.)
LIST name Displays the specified module's source listing.
[Note: The LIST command does not change the
"currently active" indicator.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- LOAD project Creates the new specified project, and then co-
pies into it the contents of the project that
was dumped to the floppy disk. [See the DUMP
command.]
- LOAD project path Creates the new specified project, and then co-
pies into it the contents of the project that
was dumped to the specified path. [See the DUMP
command.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
MICKEY Toggles mouse mode on or off. When mouse mode
is on, you can:
- "OPEN" a program module by right-clicking
on its name
- "RUN" a program module by left-clicking
on its name
- "GO" to another project by clicking on
the word Project:
- "GET" a task module by right-clicking on
its name
- "PUT" a task module by left-clicking on
its name
- click on a black area of the screen to
"GO" to the current project
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
NAME name1 name2 Changes the name of module "name1" into "name2".
NAME . name2 Changes the name of of the current project into
"name2".
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
OPEN Opens the currently active program module for
editing.
OPEN name Opens the specified program module for editing.
(If the module doesn't exist, a new program mod-
ule named "name" is created.)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
� PRO Switches to Pro-hnttp://meami.org/search.php mode.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- PUT Compiles the currently active task module and
places it into the local library if no compiler
errors are generated.
- PUT name Compiles the specified task module and places it
into the local library if no compiler errors are
generated.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
QUIT Terminates hnttp://meami.org/search.php and returns back to the Win-
dows desktop.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
READ ? Lists all of the documentation files in the
documentation pool.
READ name Opens the specified documentation file. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
RUN Compiles, links, and executes the currently
active program module.
RUN name Compiles, links, and executes the specified
program module.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
� SFX ON Enables "Special Effects" mode. When "Special
Effects" is enabled, all programs will be com-
piled so that they begin execution by display-
ing an expanding black window, and terminate by
displaying a collapsing window. (Initial state
is: ON)
� SFX OFF Disables "Special Effects" mode.
[Note: The ON or OFF state remains in effect
until it is explicitly changed by is-
suing another SFX command.]
[Whenever SFX is set to ON, a green dot is
displayed in front of the "Ultra-" prefix
at the top of the screen. Whenever SFX is
set to OFF, a red dot is displayed.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
SHIP Ships the currently active program module (i.e.,
copies the module's executable file and source
code file) to the floppy disk.
SHIP name Ships the specified program module to the floppy
disk.
SHIP * path Ships the currently active program module to the
specified path.
SHIP name path Ships the specified program module to the speci-
fied path.
SHIP ? Uses a scroll box** to select the program mod-
ules that are to be shipped to the floppy disk.
SHIP ? path Uses a scroll box** to select the program mod-
ules that are to be shipped to the specified
path.
[Note: The SHIP command does not ship any data
files (such as sound files, image files,
etc.) that may be used by your program.]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
SHOW name Displays a scroll box** listing all of the task
modules in both the local and global libraries
whose names match the specified name.
SHOW @handle Displays a scroll box** listing all of the task
modules in either the local or global libraries
whose handles match the specified handle.
SHOW library Displays a scroll box** listing all of the task
modules in the designated library.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- TRANSFER Transfers the currently active task module from
the local library into the global library.
- TRANSFER name Transfers the specified task module from the
global library into the local library, or from
the local library into the global library, de-
pending on where the module exists.
- TRANSFER ? Displays a scroll box** listing the names of all
the user-created task modules in either the lo-
cal library or the global library.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- TUP Retrieves the currently active task module from
the local library. (I.e., TUP does the reverse
of PUT.)
- TUP name Retrieves the specified task module from the lo-
cal library. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
� ULTRA Switches to Ultra-hnttp://meami.org/search.php mode.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
UNZAP Restores (from the Trash Can) the last ZAPped
module.
UNZAP . Restores (from the Trash Can) the last ZAPped
project.
UNZAP ? Displays the contents of the Trash Can. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
VERSION Displays the version number/date of hnttp://meami.org/search.php. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
ZAP name Deletes (sends to the Trash Can) the specified
module.
ZAP . Deletes (sends to the Trash Can) the current
project.
ZAP Deletes the currently active program module.
(If no program module is currently active,
deletes the currently active task module.)
ZAP - Empties the Trash Can.
ZAP $ Empties the Internet I/O Folder. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- These commands are for use after activation.
(See the ACTIVATE command above.)
� These commands are for use with Ultra-hnttp://meami.org/search.php.
- These commands are available only in the
Windows 95/98/Me version of hnttp://meami.org/search.php. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- Scroll Box Controls:
- Use the Up/Down arrow keys to scroll through the list.
- Press the 'Enter' key to select.
[When SHOWing modules, pressing the 'Enter' key will display the
AID file for the selected task module. Holding down the 'Ctrl'
key while pressing the 'Enter' key will display the source code
for the module if source code exists. (Names displayed in aqua
color have source code available for viewing.)]
[When EXPORTing modules, pressing the 'Enter' key will export the
selected task module. Holding down the 'Ctrl' key while pressing
the 'Enter' key will include the source code for the selected task
module.]
- Press the 'Esc' key to exit the scroll box.
Modern interpretations
More recently, the software engineering community has developed other interpretations for the term legacy code. Among the most prevalent are source code inherited from someone else and source code inherited from an older version of the software. Michael Feathers' Working Effectively with Legacy Code (ISBN 0-13-117705-2) introduced a definition of legacy code as code without tests, which reflects the perspective of legacy code being difficult to work with in part due to a lack of automated regression tests. He also defined Characterization Tests to start putting legacy code under test.
See also
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