b7ca945877
This patch allows you to stop auto-indent by pressing enter on a second blank line. Easier than having to use backspace, and prevents new users from getting stuck in auto-indent mode.
212 lines
6.3 KiB
ReStructuredText
212 lines
6.3 KiB
ReStructuredText
The MicroPython Interactive Interpreter Mode (aka REPL)
|
|
=======================================================
|
|
|
|
This section covers some characteristics of the MicroPython Interactive
|
|
Interpreter Mode. A commonly used term for this is REPL (read-eval-print-loop)
|
|
which will used to refer to this interactive prompt.
|
|
|
|
Auto-indent
|
|
-----------
|
|
|
|
When typing python statements which end in a colon (for example if, for, while)
|
|
then the prompt will change to three dots (...) and the cursor will be indented
|
|
by 4 spaces. When you press return, the next line will continue at the same
|
|
level of indentation for regular statements or an additional level of indentation
|
|
where appropriate. If you press the backspace key then it will undo one
|
|
level of indentation.
|
|
|
|
If your cursor is all the way back at the beginning, pressing RETURN will then
|
|
execute the code that you've entered. The following shows what you'd see
|
|
after entering a for statement (the underscore shows where the cursor winds up):
|
|
|
|
>>> for i in range(3):
|
|
... _
|
|
|
|
If you then enter an if statement, an additional level of indentation will be
|
|
provided:
|
|
|
|
>>> for i in range(30):
|
|
... if i > 3:
|
|
... _
|
|
|
|
Now enter ``break`` followed by RETURN and press BACKSPACE:
|
|
|
|
>>> for i in range(30):
|
|
... if i > 3:
|
|
... break
|
|
... _
|
|
|
|
Finally type ``print(i)``, press RETURN, press BACKSPACE and press RETURN again:
|
|
|
|
>>> for i in range(30):
|
|
... if i > 3:
|
|
... break
|
|
... print(i)
|
|
...
|
|
0
|
|
1
|
|
2
|
|
3
|
|
>>>
|
|
|
|
Auto-indent won't be applied if the previous two lines were all spaces. This
|
|
means that you can finish entering a compound statment by pressing RETURN
|
|
twice, and then a third press will finish and execute.
|
|
|
|
Auto-completion
|
|
---------------
|
|
|
|
While typing a command at the REPL, if the line typed so far corresponds to
|
|
the beginning of the name of something, then pressing TAB will show
|
|
possible things that could be entered. For example type ``m`` and press TAB
|
|
and it should expand to ``machine``. Enter a dot ``.`` and press TAB again. You
|
|
should see something like:
|
|
|
|
>>> machine.
|
|
__name__ info unique_id reset
|
|
bootloader freq rng idle
|
|
sleep deepsleep disable_irq enable_irq
|
|
Pin
|
|
|
|
The word will be expanded as much as possible until multiple possibilities exist.
|
|
For example, type ``machine.Pin.AF3`` and press TAB and it will expand to
|
|
``machine.Pin.AF3_TIM``. Pressing TAB a second time will show the possible
|
|
expansions:
|
|
|
|
>>> machine.Pin.AF3_TIM
|
|
AF3_TIM10 AF3_TIM11 AF3_TIM8 AF3_TIM9
|
|
>>> machine.Pin.AF3_TIM
|
|
|
|
Interrupting a running program
|
|
------------------------------
|
|
|
|
You can interupt a running program by pressing Ctrl-C. This will raise a KeyboardInterrupt
|
|
which will bring you back to the REPL, providing your program doesn't intercept the
|
|
KeyboardInterrupt exception.
|
|
|
|
For example:
|
|
|
|
>>> for i in range(1000000):
|
|
... print(i)
|
|
...
|
|
0
|
|
1
|
|
2
|
|
3
|
|
...
|
|
6466
|
|
6467
|
|
6468
|
|
Traceback (most recent call last):
|
|
File "<stdin>", line 2, in <module>
|
|
KeyboardInterrupt:
|
|
>>>
|
|
|
|
Paste Mode
|
|
----------
|
|
|
|
If you want to paste some code into your terminal window, the auto-indent feature
|
|
will mess things up. For example, if you had the following python code: ::
|
|
|
|
def foo():
|
|
print('This is a test to show paste mode')
|
|
print('Here is a second line')
|
|
foo()
|
|
|
|
and you try to paste this into the normal REPL, then you will see something like
|
|
this:
|
|
|
|
>>> def foo():
|
|
... print('This is a test to show paste mode')
|
|
... print('Here is a second line')
|
|
... foo()
|
|
...
|
|
Traceback (most recent call last):
|
|
File "<stdin>", line 3
|
|
IndentationError: unexpected indent
|
|
|
|
If you press Ctrl-E, then you will enter paste mode, which essentially turns off
|
|
the auto-indent feature, and changes the prompt from ``>>>`` to ``===``. For example:
|
|
|
|
>>>
|
|
paste mode; Ctrl-C to cancel, Ctrl-D to finish
|
|
=== def foo():
|
|
=== print('This is a test to show paste mode')
|
|
=== print('Here is a second line')
|
|
=== foo()
|
|
===
|
|
This is a test to show paste mode
|
|
Here is a second line
|
|
>>>
|
|
|
|
Paste Mode allows blank lines to be pasted. The pasted text is compiled as if
|
|
it were a file. Pressing Ctrl-D exits paste mode and initiates the compilation.
|
|
|
|
Soft Reset
|
|
----------
|
|
|
|
A soft reset will reset the python interpreter, but tries not to reset the
|
|
method by which you're connected to the MicroPython board (USB-serial, or Wifi).
|
|
|
|
You can perform a soft reset from the REPL by pressing Ctrl-D, or from your python
|
|
code by executing: ::
|
|
|
|
raise SystemExit
|
|
|
|
For example, if you reset your MicroPython board, and you execute a dir()
|
|
command, you'd see something like this:
|
|
|
|
>>> dir()
|
|
['__name__', 'pyb']
|
|
|
|
Now create some variables and repeat the dir() command:
|
|
|
|
>>> i = 1
|
|
>>> j = 23
|
|
>>> x = 'abc'
|
|
>>> dir()
|
|
['j', 'x', '__name__', 'pyb', 'i']
|
|
>>>
|
|
|
|
Now if you enter Ctrl-D, and repeat the dir() command, you'll see that your
|
|
variables no longer exist:
|
|
|
|
.. code-block:: python
|
|
|
|
PYB: sync filesystems
|
|
PYB: soft reboot
|
|
MicroPython v1.5-51-g6f70283-dirty on 2015-10-30; PYBv1.0 with STM32F405RG
|
|
Type "help()" for more information.
|
|
>>> dir()
|
|
['__name__', 'pyb']
|
|
>>>
|
|
|
|
The special variable _ (underscore)
|
|
-----------------------------------
|
|
|
|
When you use the REPL, you may perfom computations and see the results.
|
|
MicroPython stores the results of the previous statment in the variable _ (underscore).
|
|
So you can use the underscore to save the result in a variable. For example:
|
|
|
|
>>> 1 + 2 + 3 + 4 + 5
|
|
15
|
|
>>> x = _
|
|
>>> x
|
|
15
|
|
>>>
|
|
|
|
Raw Mode
|
|
--------
|
|
|
|
Raw mode is not something that a person would normally use. It is intended for
|
|
programmatic use. It essentially behaves like paste mode with echo turned off.
|
|
|
|
Raw mode is entered using Ctrl-A. You then send your python code, followed by
|
|
a Ctrl-D. The Ctrl-D will be acknowledged by 'OK' and then the python code will
|
|
be compiled and executed. Any output (or errors) will be sent back. Entering
|
|
Ctrl-B will leave raw mode and return the the regular (aka friendly) REPL.
|
|
|
|
The ``tools/pyboard.py`` program uses the raw REPL to execute python files on the
|
|
MicroPython board.
|
|
|