scratch3.0二次开发之用blocks生成python代码

Blockly.Python = new Blockly.Generator('Python');

Blockly.Python.addReservedWords(...);

Blockly.Python.ORDER_ATOMIC = 0;            // 0 "" ...
Blockly.Python.ORDER_COLLECTioN = 1;        // tuples, lists, dictionaries
Blockly.Python.ORDER_STRING_CONVERSION = 1; // `expression...`
Blockly.Python.ORDER_MEMBER = 2.1;          // . []
Blockly.Python.ORDER_FUNCTION_CALL = 2.2;   // ()
Blockly.Python.ORDER_EXPONENTIATION = 3;    // **
Blockly.Python.ORDER_UNARY_SIGN = 4;        // + -
Blockly.Python.ORDER_BITWISE_NOT = 4;       // ~
Blockly.Python.ORDER_MULTIPLICATIVE = 5;    // * / // %
Blockly.Python.ORDER_ADDITIVE = 6;          // + -
Blockly.Python.ORDER_BITWISE_SHIFT = 7;     // << >>
Blockly.Python.ORDER_BITWISE_AND = 8;       // &
Blockly.Python.ORDER_BITWISE_XOR = 9;       // ^
Blockly.Python.ORDER_BITWISE_OR = 10;       // |
Blockly.Python.ORDER_RELATIONAL = 11;       // in, not in, is, is not,
                                            //     <, <=, >, >=, <>, !=, ==
Blockly.Python.ORDER_LOGICAL_NOT = 12;      // not
Blockly.Python.ORDER_LOGICAL_AND = 13;      // and
Blockly.Python.ORDER_LOGICAL_OR = 14;       // or
Blockly.Python.ORDER_CONDITIONAL = 15;      // if else
Blockly.Python.ORDER_LAMBDA = 16;           // lambda
Blockly.Python.ORDER_NONE = 99;             // (...)

Blockly.Blocks['motion_movesteps'] = {
  
  init: function() {
    this.JSONInit({
      "message0": Blockly.Msg.MOTION_MOVESTEPS,
      "args0": [
        {
          "type": "input_value",
          "name": "STEPS"
        }
      ],
      "cateGory": Blockly.Categories.motion,
      "extensions": ["colours_motion", "shape_statement"]
    });
  }
};

 Blockly.Python['motion_movesteps'] = function (block) {
        var steps = Blockly.Python.valueToCode(block, "STEPS", Blockly.Python.ORDER_NONE);
        return 'move ' + steps + ' steps\n';
    };

<block type="motion_movesteps">
            <value name="STEPS">
                <shadow type="math_number">
                    <field name="NUM">10</field>
                </shadow>
            </value>
        </block>

Blockly.Python['math_number'] = function(block) {
  // Numeric value.
  var code = parseFloat(block.getFieldValue('NUM'));
  var order;
  if (code == Infinity) {
    code = 'float("inf")';
    order = Blockly.Python.ORDER_FUNCTION_CALL;
  } else if (code == -Infinity) {
    code = '-float("inf")';
    order = Blockly.Python.ORDER_UNARY_SIGN;
  } else {
    order = code < 0 ? Blockly.Python.ORDER_UNARY_SIGN :
            Blockly.Python.ORDER_ATOMIC;
  }
  return [code, order];
}

 this.workspace.addChangeListener(this.generatPythonCode);