小编esw*_*s13的帖子

当我尝试使用a static const来初始化a时unique_ptr,我得到一个"未定义的引用"错误.但是,当我new使用相同的常量指针时,符号似乎是神奇地定义的.

这是一个重现错误的简单程序:

Outside_library.h

class Outside_library
{
public:
  static const int my_const = 100;
};

main.cpp中

#include "Outside_library.h"

#include <iostream>
#include <memory>

class My_class
{
public:
  My_class(int num)
  {
    m_num = num;
  };

  virtual ~My_class(){};

private:
  int m_num;
};

int main(int, char* [])
{
  My_class* p_class = new My_class(Outside_library::my_const);
  delete p_class;

  // ==== ERROR HERE: When I comment this line out, the program runs fine.
  std::unique_ptr<My_class> p_unique
      = std::make_unique<My_class>(Outside_library::my_const);

  std::cout << "I made it …

我正在尝试显示用户已上传的图像，但是无论如何我都会得到断开的链接图标。我搜索了SO和其他地方的文档，搜索了两天，但无济于事。我是Django新手，目前正在开发中，因此，我确定我还犯了一些其他菜鸟错误，但是现在，我唯一关心的就是在模板中显示上载的图像。

以下是我的代码的相关片段：

settings.py

MEDIA_URL = '/media/media_root/'
MEDIA_ROOT = os.path.join(os.path.dirname(BASE_DIR), "media", "media_root")

urls.py

urlpatterns = [
    url(r'^admin/?', admin.site.urls),
    url(r'^accounts/', include('registration.backends.simple.urls')),
    url(r'^about/?', profiles.views.about, name='about'),
    url(r'^properties/single/?', properties.views.single, name='single_mens'),
    url(r'^properties/married/?', properties.views.married, name='married'),
    url(r'^properties/add/add_photos/?', properties.views.add_photos, name='add_photos'),
    url(r'^properties/add/?', properties.views.add_rental, name='add_rental'),
    url(r'^', profiles.views.home, name='home'),
] 

urlpatterns += static(settings.STATIC_URL, document_root=settings.STATIC_ROOT)
urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
urlpatterns += staticfiles_urlpatterns()

models.py

class RentalPicModel(models.Model):

    def __unicode__(self):
        return self.image.url

    image = models.ImageField(upload_to="pics/originals/", null=True)
    rental = models.ForeignKey(RentalModel, on_delete=models.CASCADE)

表格

class AddPhotosForm(forms.ModelForm):

    class Meta:
        model = RentalPicModel
        fields = ['image', 'rental']

    def clean_image(self):
        return self.cleaned_data['image'] …