[英]No matching function for call in Arduino Library
I am creating an Arduino library for use in a Sketch. 我正在创建一个在Sketch中使用的Arduino库。 It uses the Encoder Library , but when compiling I get an obtuse error: 它使用了Encoder库 ,但是在编译时出现了一个钝角错误:
/var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.cpp: In constructor 'MIDIEncoder::MIDIEncoder(uint8_t, uint8_t, byte, byte)': MIDIEncoder.cpp:8: error: no matching function for call to 'Encoder::Encoder()' MIDIEncoder::MIDIEncoder(uint8_t pinA, uint8_t pinB, byte midiChannel, byte midiCCNumber) ^ /var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.cpp:8:89: note: candidates are: In file included from /var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.h:17:0, from /var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.cpp:2: /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:72:2: note: Encoder::Encoder(uint8_t, uint8_t) Encoder(uint8_t pin1, uint8_t pin2) { ^ /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/l /var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.cpp:在构造函数``MIDIEncoder :: MIDIEncoder(uint8_t,uint8_t,Encoding:En错:字节:字节:'':)用于调用'Encoder :: Encoder()'MIDIEncoder :: MIDIEncoder(uint8_t pinA,uint8_t pinB,字节midiChannel,字节midiCCNumber)^ / var / folders / jy / f8dvlhcd4vdcvtl49bk8ytwc0000gn / T / builda847c0675e0bee2f5t5a。 8:89:注意:候选者是:在/var/folders/jy/f8dvlhcd4vdcvtl49bk8ytwc0000gn/T/builda847c0675e0bee2f5f05581e35ae65fe.tmp/sketch/MIDIEncoder.h:17:0的文件中,从/ var / folders / jy / f8dv0 builda847c0675e0bee2f5f05581e35ae65fe.tmp / sketch / MIDIEncoder.cpp:2:/Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:72:2:注意:Encoder :: Encoder(uint8_t, uint8_t)编码器(uint8_t pin1,uint8_t pin2){^ /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/l ibraries/Encoder/Encoder.h:72:2: note: candidate expects 2 arguments, 0 provided /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7: note: constexpr Encoder::Encoder(const Encoder&) class Encoder ^ /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7: note: candidate expects 1 argument, 0 provided /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7: note: constexpr Encoder::Encoder(Encoder&&) /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7: note: candidate expects 1 argument, 0 provided no matching function for call to 'Encoder::Encoder()' ibraries / Encoder / Encoder.h:72:2:注意:候选人需要2个参数,提供了0个/Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7:注意:constexpr Encoder :: Encoder(const Encoder&)类Encoder ^ /Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7:注意:候选人需要1个参数,提供了0个/Applications/Arduino.app/Contents/Java/hardware/teensy/avr/libraries/Encoder/Encoder.h:69:7:注意:constexpr Encoder :: Encoder(Encoder &&)/Applications/Arduino.app/Contents/ Java /硬件/teensy/avr/libraries/Encoder/Encoder.h:69:7:注意:考生期望1个参数,0提供了不匹配的函数来调用'Encoder :: Encoder()'
Fundamentally, I believe the compiler is telling me it can't find a constructor for the Encoder library MIDIEncoder.cpp:8: error: no matching function for call to 'Encoder::Encoder()'
, but I'm stumped as to why. 从根本上讲,我相信编译器会告诉我找不到编码器库MIDIEncoder.cpp:8: error: no matching function for call to 'Encoder::Encoder()'
的构造函数MIDIEncoder.cpp:8: error: no matching function for call to 'Encoder::Encoder()'
,但是我很困惑为什么。 Below is the full source for my library. 以下是我图书馆的完整资源。
MIDIEncoder.h MIDIEncoder.h
/*
MIDIEncoder.h
A library for creating relative MIDI CC messages from a rotary encoder.
Created by Paul Williamson, 11 August 2016.
Project source available at:
http://github.com/squarefrog/teensy-midi-encoder-box
Released into the public domain.
*/
#ifndef MIDIEncoder_h
#define MIDIEncoder_h
#include "Arduino.h"
#include <Encoder.h>
class MIDIEncoder
{
public:
MIDIEncoder(uint8_t pin1, uint8_t pin2, byte midiChannel, byte midiCCNumber);
byte channel;
byte ccNumber;
byte read();
private:
unsigned long _lastTurnedTime;
long _oldPosition;
Encoder _enc;
};
#endif
MIDIEncoder.cpp MIDIEncoder.cpp
#include "MIDIEncoder.h"
#include <Encoder.h>
const byte incrementValue = 66; // A constant for the start of increment values
const byte decrementValue = 2; // A constant for the start of decrement values
MIDIEncoder::MIDIEncoder(uint8_t pin1, uint8_t pin2, byte midiChannel, byte midiCCNumber)
{
channel = midiChannel;
ccNumber = midiCCNumber;
_enc = Encoder(pin1, pin2);
_oldPosition = -999;
_lastTurnedTime = millis();
}
byte MIDIEncoder::read()
{
long newPosition = _enc.read();
// If position hasn't changed, ignore.
if (newPosition == _oldPosition) {
return 0;
}
// If position is not divisible by 4, ignore.
if (newPosition % 4 != 0) {
return 0;
}
unsigned long delta = millis() - _lastTurnedTime;
byte offset = 0;
// Apply crude acceleration
if (delta < 100) offset = 4;
if (delta > 99 && delta < 180) offset = 2;
if (delta > 179 && delta <= 250) offset = 1;
_lastTurnedTime = millis();
// Return MIDI CC value
if (newPosition > _oldPosition) {
return incrementValue + offset;
} else {
return decrementValue + offset;
}
}
Some excellent answers below. 以下是一些出色的答案。 Now that I know what to look for I found this resource which explains where I made my mistake. 现在,我知道要查找的内容了,我找到了此资源 , 该资源解释了我犯错的地方。 In particular look at number 3. 特别要看数字3。
Encoder
doesn't have a default constructor, and it is implicitly call here Encoder
没有默认构造函数,在此处隐式调用
MIDIEncoder::MIDIEncoder(uint8_t pin1, uint8_t pin2, byte midiChannel, byte midiCCNumber)
/*Implicit constructor call*/
{
//...
}
You tried to call it the the constructor body, but by then "it is too late" :) What I mean is, _enc
has to be already initialized when the constructor body executes, but _enc
can't be default initialized, so the compiler complains. 您试图将其称为构造函数体,但是到那时“为时已晚” :)我的意思是,构造函数体执行时_enc
必须已经初始化,但是_enc
不能默认初始化,因此编译器抱怨。
That's what the constructor initializer list is for: 这就是构造函数初始化器列表的用途:
MIDIEncoder::MIDIEncoder(uint8_t pin1, uint8_t pin2, byte midiChannel, byte midiCCNumber)
: _enc(pin1, pin2) //Calls appropriate constructor for _enc, not default
{
//...
}
You're initializing your _enc
object too late. 您初始化_enc
对象为时已晚。
In the beginning of the MIDIEncoder constructor body _enc
should already be created, so the compiler tries to instantiate it using the (missing) default constructor and fails. 在MIDIEncoder构造体的开头_enc
应该已经被创建,所以编译器将尝试使用(丢失)默认构造函数和失败,实例化。
Initialize it in the constructor initialization list instead: 而是在构造函数初始化列表中对其进行初始化:
MIDIEncoder::MIDIEncoder(uint8_t pin1, uint8_t pin2, ...) : _enc(pin1, pin2)
{
Actually, the same is true for other variables - there is no reason to initialize it inside constructor body. 实际上,其他变量也是如此-没有理由在构造函数体内对其进行初始化。
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