code
— 解释器基类
¶
源代码： Lib/code.py
code
module provides facilities to implement read-eval-print loops in Python. Two classes and convenience functions are included which can be used to build applications which provide an interactive interpreter prompt.
代码。
InteractiveInterpreter
(
locals=None
)
¶
This class deals with parsing and interpreter state (the user’s namespace); it does not deal with input buffering or prompting or input file naming (the filename is always passed in explicitly). The optional
locals
argument specifies the dictionary in which code will be executed; it defaults to a newly created dictionary with key
'__name__'
设为
'__console__'
and key
'__doc__'
设为
None
.
代码。
InteractiveConsole
(
locals=None
,
filename="<console>"
)
¶
Closely emulate the behavior of the interactive Python interpreter. This class builds on
InteractiveInterpreter
and adds prompting using the familiar
sys.ps1
and
sys.ps2
, and input buffering.
代码。
interact
(
banner=None
,
readfunc=None
,
local=None
,
exitmsg=None
)
¶
Convenience function to run a read-eval-print loop. This creates a new instance of
InteractiveConsole
and sets
readfunc
to be used as the
InteractiveConsole.raw_input()
method, if provided. If
local
is provided, it is passed to the
InteractiveConsole
constructor for use as the default namespace for the interpreter loop. The
interact()
method of the instance is then run with
banner
and
exitmsg
passed as the banner and exit message to use, if provided. The console object is discarded after use.
3.6 版改变： 添加 exitmsg 参数。
代码。
compile_command
(
source
,
filename="<input>"
,
symbol="single"
)
¶
This function is useful for programs that want to emulate Python’s interpreter main loop (a.k.a. the read-eval-print loop). The tricky part is to determine when the user has entered an incomplete command that can be completed by entering more text (as opposed to a complete command or a syntax error). This function almost always makes the same decision as the real interpreter main loop.
source
is the source string;
filename
is the optional filename from which source was read, defaulting to
'<input>'
; and
symbol
is the optional grammar start symbol, which should be either
'single'
(默认) 或
'eval'
.
Returns a code object (the same as
compile(source,
filename,
symbol)
) if the command is complete and valid;
None
if the command is incomplete; raises
SyntaxError
if the command is complete and contains a syntax error, or raises
OverflowError
or
ValueError
if the command contains an invalid literal.
InteractiveInterpreter.
runsource
(
source
,
filename="<input>"
,
symbol="single"
)
¶
Compile and run some source in the interpreter. Arguments are the same as for
compile_command()
; the default for
filename
is
'<input>'
, and for
symbol
is
'single'
. One several things can happen:
compile_command()
raised an exception (
SyntaxError
or
OverflowError
). A syntax traceback will be printed by calling the
showsyntaxerror()
方法。
runsource()
返回
False
.
compile_command()
returned
None
.
runsource()
返回
True
.
compile_command()
returned a code object. The code is executed by calling the
runcode()
(which also handles run-time exceptions, except for
SystemExit
).
runsource()
返回
False
.
The return value can be used to decide whether to use
sys.ps1
or
sys.ps2
to prompt the next line.
InteractiveInterpreter.
runcode
(
code
)
¶
Execute a code object. When an exception occurs,
showtraceback()
is called to display a traceback. All exceptions are caught except
SystemExit
, which is allowed to propagate.
A note about
KeyboardInterrupt
: this exception may occur elsewhere in this code, and may not always be caught. The caller should be prepared to deal with it.
InteractiveInterpreter.
showsyntaxerror
(
filename=None
)
¶
Display the syntax error that just occurred. This does not display a stack trace because there isn’t one for syntax errors. If
filename
is given, it is stuffed into the exception instead of the default filename provided by Python’s parser, because it always uses
'<string>'
when reading from a string. The output is written by the
write()
方法。
InteractiveInterpreter.
showtraceback
(
)
¶
Display the exception that just occurred. We remove the first stack item because it is within the interpreter object implementation. The output is written by the
write()
方法。
3.5 版改变： The full chained traceback is displayed instead of just the primary traceback.
InteractiveInterpreter.
write
(
data
)
¶
Write a string to the standard error stream (
sys.stderr
). Derived classes should override this to provide the appropriate output handling as needed.
InteractiveConsole
类是子类化的
InteractiveInterpreter
, and so offers all the methods of the interpreter objects as well as the following additions.
InteractiveConsole.
interact
(
banner=None
,
exitmsg=None
)
¶
Closely emulate the interactive Python console. The optional banner argument specify the banner to print before the first interaction; by default it prints a banner similar to the one printed by the standard Python interpreter, followed by the class name of the console object in parentheses (so as not to confuse this with the real interpreter – since it’s so close!).
可选
exitmsg
argument specifies an exit message printed when exiting. Pass the empty string to suppress the exit message. If
exitmsg
is not given or
None
, a default message is printed.
3.4 版改变： 要抑制打印任何标语，请传递空字符串。
3.6 版改变： 打印退出消息，当退出时。
InteractiveConsole.
push
(
line
)
¶
Push a line of source text to the interpreter. The line should not have a trailing newline; it may have internal newlines. The line is appended to a buffer and the interpreter’s
runsource()
method is called with the concatenated contents of the buffer as source. If this indicates that the command was executed or invalid, the buffer is reset; otherwise, the command is incomplete, and the buffer is left as it was after the line was appended. The return value is
True
if more input is required,
False
if the line was dealt with in some way (this is the same as
runsource()
).
InteractiveConsole.
resetbuffer
(
)
¶
从输入缓冲移除任何未处理源文本。
InteractiveConsole.
raw_input
(
prompt=""
)
¶
Write a prompt and read a line. The returned line does not include the trailing newline. When the user enters the EOF key sequence,
EOFError
is raised. The base implementation reads from
sys.stdin
; a subclass may replace this with a different implementation.